Abstract:
The invention provides a method of lubricating an end-pivot finger follower valve train lash adjuster of a passenger car compression ignition internal combustion engine having a reference mass not exceeding 2610 kg comprising supplying to the internal combustion engine a lubricating composition comprising an oil of lubricating viscosity 0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of (typically 3000 to 12,000 ppm).

Description:
FIELD OF INVENTION 
       [0001]    The invention provides a method of lubricating an end-pivot finger follower valve train lash adjuster of a passenger car compression ignition internal combustion engine having a reference mass not exceeding 2610 kg comprising supplying to the internal combustion engine a lubricating composition comprising an oil of lubricating viscosity 0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of 12,000 ppm or less, or 10,000 ppm or less. 
       BACKGROUND OF THE INVENTION 
       [0002]    The valve train of internal combustion engines is known to vary in both the design and with fuel type. For example the fuel type may be gasoline or diesel; and the valve train may have general types of configuration such as a direct acting cam and bucket, an end-pivot finger follower, a push rod or a rocker arm. The valve train types are described in “Valve Train Components, Technology Failure Diagnosis”, published by Schaeffler (see www.schaeffler-Aftermarket.com, with serial number 94410002202266/0/0/1/2010/PDF-GB). When considering valve-train designs from a tribological standpoint as it interacts with a lubricant, the specific type of valve-train, the slide to roll ratio between contacts and the metallurgy can all affect the lubrication regime differently, meaning that engine metallurgy, contact pressure, speed of contact, surface finish, sliding versus rolling contact (or slide to roll ratio) all affect the way in which lubricant additives interact and contribute towards reducing wear, corrosion, or fatigue of engine components. 
         [0003]    For example, the differences in engine design allow for different types of valve train design. Valve-train designs are selected by original equipment manufacturer (OEM) depending upon design requirements for their engine and whilst there is no “best” design for an engine, the OEM considers design factors including valve-train design in combination other factors such as different fuel types and engine size. 
         [0004]    Heavy duty diesel engines are noted to be limited to all motor vehicles with a “technically permissible maximum laden mass” over 3,500 kg, equipped with compression ignition engines or positive ignition natural gas (NG) or LPG engines. In contrast, the European Union indicates that for new light duty vehicles (passenger cars and light commercial vehicles) included within the scope of ACEA testing section “C” have a “technically permissible maximum laden mass” not exceeding 2610 kg. (Is my change correct?) 
         [0005]    There is a distinct difference between passenger car, and heavy duty diesel engines. The difference in size from over 3,500 kg to not more than 2610 kg means that engines of both types will experience significantly different operating conditions such as load, oil temperatures, duty cycle and engine speeds. Heavy duty diesel engines are designed to maximize torque for hauling payloads at maximum fuel economy while passenger car diesels are designed for commuting people and acceleration at maximum fuel economy. The designed purpose of the engine hauling versus communing results in different hardware designs and resulting stresses imparted to lubricant designed to protect and lubricate the engine. Another distinct design difference is the operating revolution per minute (RPM) that each engine operates at to haul versus commute. A heavy duty diesel engine such as a typical 12-13 litre truck engine would typically not exceed 2200 rpm while a passenger car engine can go up to 4500 rpm. The difference in rpm between a heavy duty diesel engine and a passenger car means that because of the more extreme operating conditions a passenger car lubricant will be exposed to higher operating temperatures, higher shear, increased oxidation and deposit rates. 
         [0006]    For many years engine design has focused on heavy duty diesel and gasoline engines that have a valve train comprising a direct acting cam and bucket, or a rocker arm. The prior art references summarised below emphasizes the efforts undertaken to improve engine lubricant design to enhance soot handling for heavy duty diesel engines such as Mack T-10 or T-11, or minimisation of wear or sludge formation in gasoline engines such as those required for GF-3 approval or Sequence IIIF approval, or Peugeot TU3M engine. Efforts have been made to reduce deposit formation in cam- and bucket valve train TDi Volkswagon engines. 
         [0007]    US 2013/0143781 (Barton et al., published 20 May 2013) discloses a method of lubricating an internal combustion engine and a lubricating composition comprising an oil of lubricating viscosity and 0.1 wt % to 70 wt % of a copolymer comprising units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof, esterified and amidated with an alcohol and an aromatic amine respectively, wherein the copolymer is obtained by a process comprising: (1) reacting monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof to form a copolymer; (2) reacting the product of step (1) with an aromatic amine; and (3) reacting the copolymer of step (2) with an alcohol, to form a copolymer that is amidated and esterified. 
         [0008]    US 2013/0143780 (Gieselman et al, published 20 May 2013) discloses a lubricating composition comprising an oil of lubricating viscosity and a compound comprising the reaction product of a polyolefin, an ethylenically unsaturated aromatic acylating agent (or carboxylic reactant), and an amine. In one embodiment the amine is an acyclic polyamine, the polyolefin is a polybutene, and the lubricating composition has a sulphated ash content of 0.3 wt % to 1.2 wt % of the lubricating composition. The lubricating composition is disclosed for use in an internal combustion engine having a surface of steel or aluminium (typically a surface of steel). 
         [0009]    US 2012/0184473 (Boffa et al., published 20 Dec. 2012) discloses a lubricating oil composition comprising: i) a major amount of a base oil, ii) at least one oil-soluble molybdenum compound and iii) a zinc dialkyldithiophosphate compound, wherein the molybdenum content derived from the molybdenum compound is at least 10 ppm Molybdenum based on the total weight of the lubricating oil composition and the phosphorus content derived from the zinc dialkyldithiophosphate compound is about 200 ppm to 500 ppm based on the total weight of the lubricating oil composition. The method of lubricating a motor engine comprising the step of operating the engine with the lubricating oil composition is also disclosed. 
         [0010]    US 2012/0046206 (Gieselman et al., published 23 Feb. 2012) discloses a lubricating composition comprising an oil of lubricating viscosity, a dispersant and an amine-functionalised additive, wherein the amine-functionalised additive is derived from an amine having at least 3 or 4 aromatic groups, wherein the amine-functionalised additive is a product obtained/obtainable by reacting the amine having at least 3 aromatic groups with a carboxylic functionalised polymer. The lubricants are used in a Mack T 11 test, and further exemplify the use of sulphurised olefin antioxidant in an unspecified amount. 
         [0011]    US 2009/0325831 (Mathur et al., published 30 Jun. 2008) discloses a lubricating composition comprising: a major amount of an oil of lubricating viscosity; and a minor amount of an additive concentrate comprising a viscosity index modifying copolymer comprising the reaction product of an acylated ethylene-olefin copolymer and a polyamine, wherein the polyamine comprises at least two primary or secondary amine functional group. The lubricating composition is disclosed as useful for a method of lubricating an automotive engine. 
         [0012]    US 2009/0305923 (Visger et al., published 10 Dec. 2009) discloses in a lubricant a composition comprising a major amount of an oil of lubricating viscosity and a minor amount of the an esterified, nitrogen-functionalized interpolymer composition derived from monomers comprising (i) at least one monomer selected from (a) vinyl aromatic monomers, and (ii) at least one α,β-unsaturated acylating agent; wherein a portion of said acylating agent-derived units is esterified and wherein a portion of said acylating agent-derived units is condensed with at least one aromatic amine containing at least one N—H group capable of condensing with the acylating agent monomer-derived unit, the amine being selected from the group consisting of 4-aminodiphenylamine, 4-phenylazoaniline, 2-aminobenzimidazole, and 3-nitroaniline. The lubricant is disclosed as useful for reducing soot-induced viscosity increase in heavy duty diesel engines and exemplified in Mack T-11 test. 
         [0013]    US 2008/182768 (Devlin et al., published 31 Jul. 2008) discloses improved lubricant compositions for bio-diesel fuel engine. The bio diesel engine operate on a fuel containing from about 5 to about 100 wt. % bio-diesel components and is lubricated with a lubricating oil composition comprising a major amount of oil of lubricating viscosity, and a minor amount of at least one highly grafted, multi-functional olefin copolymer made by reacting an acylating agent with an olefin copolymer having a number average molecular weight greater than about 1,000 in the presence of a free radical initiator to provide an acylated olefin copolymer having a degree of grafting (DOG) of the acylating agent on the olefin copolymer of at least 0.5 wt. %, and reacting the acylated olefin copolymer with an amine to provide the highly grafted, multi-functional olefin copolymer, wherein the highly grafted, multi-functional olefin copolymer is effective to reduce a viscosity increase in the lubricating oil composition for the engine to less than or equal to a viscosity increase in a lubrication oil composition for an engine operating on a fuel devoid of the bio-diesel components. The lubricant performs in the T-11 soot deposit test. 
         [0014]    US 2007/0111904 (Van Dam, published 17 May, 2007) discloses a low sulfur and low phosphorus lubricating oil composition comprising: (a) a major amount of an oil of lubricating viscosity; (b) one or more dispersants; (c) one or more anti-oxidants; and (d) one or more detergents; wherein the lubricating oil composition is essentially free of zinc di-alkyl di-thiophosphates and contains no more than 0.1 weight percent sulfur and provided the lubricating oil composition does not contain alkylated and non-alkylated aromatic amines and tri-nuclear molybdenum compounds. The lubricant is evaluated in a Mack T-10 diesel engine cylinder liner wear test. 
         [0015]    US 2006/0264342 (Shaw et al, published 23 Nov. 2006) discloses a method of lubricating an internal combustion engine having a cam and a rotating tappet, the method comprising employing as the lubricant for the engine a lubricating composition comprising a base oil of lubricating viscosity, phosphorus in an amount of from 50 to 900 ppm by mass, sulfur in an amount of from 1500 to 3000 ppm by mass, boron in an amount of from 0.0 to 100 ppm, sulphated ash in an amount not exceeding 1.0 mass %, and friction modifier in an amount of from 0.0 to 0.1 mass %, said amounts being based on the mass of fully formulated lubricating oil composition. Preferred lubricating compositions also contain a viscosity index improver dispersant. Examples of viscosity index improver dispersants include reaction products of amines, for example polyamines, with a hydrocarbyl-substituted mono- or dicarboxylic acid in which the hydrocarbyl substituent comprises a chain of sufficient length to impart viscosity index improving properties to the compounds. In general, the viscosity index improver dispersant may be, for example, a polymer of a C4 to C24 unsaturated ester of vinyl alcohol or a C3 to C10 unsaturated mono-carboxylic acid or a C4 to C10 di-carboxylic acid with an unsaturated nitrogen-containing monomer having 4 to 20 carbon atoms; a polymer of a C2 to C20 olefin with an unsaturated C3 to C10 mono- or di-carboxylic acid neutralised with an amine, hydroxyamine or an alcohol; or a polymer of ethylene with a C3 to C20 olefin further reacted either by grafting a C4 to C20 unsaturated nitrogen-containing monomer thereon or by grafting an unsaturated acid onto the polymer backbone and then reacting carboxylic acid groups of the grafted acid with an amine, hydroxy amine or alcohol. 
         [0016]    US 2003/0148895 (Robson et al., published 9 Nov. 2001) discloses a lubricating oil compositions intended to reduce wear in the Peugeot TU3M gasoline Scuffing Test. This test is intended to investigate wear on the cam and tappets of an internal combustion engine. The disclosures of this document show that relatively high levels of boron (derived from borated dispersant) and preferably augmented with significant amount of molybdenum (derived from, e.g., a trinuclear molybdenum additive) are required to reduce cam and tappet wear to acceptable levels. 
         [0017]    US 2006/0205614 (Artman et al., published 14 Sep. 2006) discloses a low-sulfur, low-phosphorus composition suitable for lubricating a compression ignited internal combustion engine, comprising: (a) an oil of lubricating viscosity; (b) a substantially nitrogen-free sulfurized olefin antiwear agent, in an amount sufficient to provide improved antiwear performance to the composition; (c) about 1 to about 10 percent by weight of a nitrogen-containing dispersant; and (d) an overbased detergent selected from the group consisting of salixarates, saligenins, salicylates, glyoxylates, and mixtures thereof; said composition containing less than about 0.1 percent by weight phosphorus, less than about 0.4 percent by weight sulfur, and having less than about 1.2% sulfated ash. The internal combustion engine exemplified is an API CH-4 Cummins M11 heavy duty diesel engine. 
         [0018]    U.S. Pat. No. 8,420,583 (Boegner et al., published 22 May, 2003) discloses a lubricating oil composition comprising: a major amount of oil of lubricating viscosity; and a minor amount of at least one highly grafted, multi-functional olefin copolymer made by reacting an acylating agent with an olefin copolymer having a number average molecular weight greater than about 10,000 up to about 50,000 in the presence of a free radical initiator to provide an acylated olefin copolymer having a degree of grafting (DOG) of the acylating agent on the olefin copolymer of from above about 1.5 to about 3.0 wt. %, and reacting the acylated olefin copolymer with an amine to provide the highly grafted, multi-functional olefin copolymer. The lubricating compositions are disclosed for lubricating compression ignited internal combustion engines for reducing soot deposits. 
         [0019]    U.S. Pat. No. 8,168,574 (Visger et al., published 10 Dec. 2009) discloses reducing soot-induced viscosity increase in heavy duty diesel engines. The lubricating composition disclosed therein comprises an oil of lubricating viscosity and an esterified, nitrogen-functionalized interpolymer composition derived from monomers comprising (i) at least one monomer selected from (a) vinyl aromatic monomers, and (ii) at least one α,β-unsaturated acylating agent; wherein a portion of said acylating agent-derived units is esterified and wherein a portion of said acylating agent-derived units is condensed with at least one aromatic amine containing at least one N—H group capable of condensing with said acylating agent monomer-derived unit, said amine being selected from the group consisting of 4-aminodiphenylamine, 4-phenylazoaniline, 2-aminobenzimidazole, and 3-nitroaniline. 
         [0020]    U.S. Pat. No. 8,093,189 (Devlin et al., published 13 Mar., 2008) discloses a low SAP lubricating oil composition for heavy-duty diesel engines, and particularly CJ-4, CI-4 PLUS or CI-4 engines comprising a major amount of oil of lubricating viscosity and a minor amount of an amine-functionalized olefin copolymer dispersant viscosity index improver comprising the reaction product of an acylated olefin copolymer and a polyamine compound, wherein the olefin copolymer dispersant viscosity index improver is present in an amount effective to inhibit coolant-induced filter plugging, as measured by the Cummins ISM EGR Test, upon the lubricating oil composition being contaminated by about 2 percent engine coolant composed of an approximately 50:50 mixture of water and pure (poly)ethylene glycol (total), relative to a modified form of the lubricating oil composition which instead contains a non-amine functionalized, non-acylated form of the olefin copolymer dispersant but otherwise is the same. 
         [0021]    US 2006/025316 (Covitch et al., published 2 Feb. 2006) discloses a method for lubricating a heavy-duty diesel engine equipped with exhaust gas recirculation, comprising supplying thereto a composition comprising an oil of lubricating viscosity and the reaction product of: (a) a polymer comprising carboxylic acid functionality or a reactive equivalent thereof, said polymer having a number average molecular weight of greater than 5,000; and (b) an amine component comprising at least one aromatic amine containing at least one amino group capable of condensing with said carboxylic acid functionality to provide a pendant group and at least one additional group comprising at least one nitrogen, oxygen, or sulfur atom, wherein said aromatic amine is selected from the group consisting of (i) a nitro-substituted aniline (such as 3-nitroaniline), (ii) amines comprising two aromatic moieties linked by a —C(O)NR— group, a —C(O)O— group, an —O— group, an —N—N— group, or an —SO2- group, where R is hydrogen or hydrocarbyl, one of said aromatic moieties bearing said condensable amino group, (iii) an aminoquinoline, (iv) an aminobenzimidazole, (v) an N,N-dialkylphenylenediamine, and (vi) a ring-substituted benzylamine. 
         [0022]    US 2004/038836 (Devlin et al., published 26 Feb. 2004) discloses a lubricant suitable for use in a diesel engine comprising: a lubricating oil having a viscosity suitable for use in a diesel engine; at least one functionalized olefin polymer; and a zinc dialkyl dithiophosphate (ZDDP) wherein the ZDDP is made from a mixture of primary alcohols or a mixture of primary and secondary alcohols, wherein the lubricant has high boundary film friction value as measured by using a High Frequency Reciprocating Rig (HFRR) of greater than or equal to 15. 
         [0023]    US 2003/134754 (Kelley, published 17 Jul. 2003) discloses a composition comprising: (a) a major amount of an API Group I mineral oil base stock containing at least 300 ppm sulfur by weight; (b) a molybdenum dithiocarbamate in an amount suitable to provide about 25 to about 600 ppm molybdenum to the composition; (c) a succinimide dispersant based on a polyolefin-substituted succinic structure, where the polyolefin has a number average molecular weight of at least about 1300; (d) a zinc dialkyldithiophosphate derived from at least one secondary alcohol; and (e) at least one oxidation inhibitor selected from the group consisting of hindered phenols, alkylated aromatic amines, and sulfurized olefins. The composition is noted as useful for lubricating engine oils formulated the meet the new specifications of ILSAC GF-3 using conventional high sulfur base stocks and tested in Sequence IIIF gasoline engine. 
         [0024]    For a passenger car diesel engine designed having an end-pivot finger follower valve train with a lash adjuster, fewer studies have been reported attempting to improve lubricant performance by reducing wear. As a result, Peugeot have introduced a test method entitled DW10 Lash Adjuster Test, run at APL testing laboratory (Automobil-Prüftechnik Landau GmbH) for engine having this design. A lubricant must obtain a wear rating of 7 or higher to pass the wear requirements of this test. The objective of the present invention is to reduce wear in passenger car diesel engine having an end-pivot finger follower valve train with a lash adjuster and in a specific embodiment have a wear rating of greater than 7 as measured in the DW10 Lash Adjuster Test. 
       SUMMARY OF THE INVENTION 
       [0025]    As used herein reference to the amounts of additives present in the lubricating composition disclosed herein are quoted on an oil free basis, i.e., amount of actives, unless otherwise indicated. 
         [0026]    As used herein, the transitional term “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, un-recited elements or method steps. However, in each recitation of “comprising” herein, it is intended that the term also encompass, as alternative embodiments, the phrases “consisting essentially of” and “consisting of,” where “consisting of” excludes any element or step not specified and “consisting essentially of” permits the inclusion of additional un-recited elements or steps that do not materially affect the basic and novel characteristics of the composition or method under consideration. 
         [0027]    The invention relates to a method of lubricating an end-pivot finger follower valve train lash adjuster of a passenger car compression ignition internal combustion engine having a reference mass not exceeding 2610 kg comprising supplying to the internal combustion engine a lubricating composition comprising an oil of lubricating viscosity 0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of (typically 3000 to 12,000 ppm), or 10,000 ppm or less. 
         [0028]    The passenger car reference mass not exceeding 2610 kg is a technical feature defined by the European Union as specified in Euro 5 and 6 emission requirements. The same standard is applied by the professional industry association ACEA (European Automobile Manufacturers Association) such that it defines a light passenger car in Section C of the ACEA European Oil Sequences for 2010. As such the method of the present invention relates to lubricating a light passenger car compression ignition internal combustion engine (a diesel engine) comprising an end-pivot finger follower valve train lash adjuster. 
         [0029]    The lubricating composition may have a sulphur-content of 500 to 4000 ppm, or 1000 to 3000 ppm, a phosphorus content of 300 to 900 ppm, or 400 to 750 ppm, and a sulphated ash content of 3000 to 7000 ppm. 
         [0030]    The lubricating composition may comprise a zinc free sulphur-containing antiwear agent comprising 0.1 to 0.5 wt % sulphurised olefin, and 0.1 to 0.5 wt % of an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
         [0031]    The lubricating composition may comprise 0.1 wt % to 0.4 wt % of molybdenum dithiocarbamate a zinc free sulphur-containing antiwear agent, and 0.1 to 0.5 wt %, an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
         [0032]    The lubricating composition disclosed herein may further comprise calcium sulphonate overbased detergent present at 0.01 to 0.5 wt %, or 0.05 to 0.3 wt % of the lubricating composition (typically wherein the calcium sulphonate overbased detergent has a TBN of 300 to 500 mg KOH/g). 
         [0033]    The lash adjuster typically comprises a ball and socket joint. 
         [0034]    The lash adjuster typically is a hydraulic lash adjuster. 
         [0035]    The lash adjuster is typically a hydraulic lash adjuster comprising a ball and socket joint. In one embodiment the lash adjuster does not have a chrome coating, a tin coating, a nitride coating, or a boride coating. 
         [0036]    The invention further provides for the method or use of a lubricating composition comprising: 
         [0037]    an oil of lubricating viscosity, 
         [0038]    0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 
         [0039]    0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, 
         [0000]    wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of typically 3000 to 12,000 ppm, or 10,000 ppm or less,
 
to reduce wear in an internal combustion engine comprising an end-pivot finger follower valve train lash adjuster.
 
         [0040]    The reduction in wear may be measured by Peugeot DW10 Lash Adjuster Test with a pass rating of 7 or higher. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]    The present invention provides a method for lubricating an internal combustion engine and a use as disclosed above. 
       Oils of Lubricating Viscosity 
       [0042]    The lubricating composition comprises an oil of lubricating viscosity. Such oils include natural and synthetic oils, oil derived from hydrocracking, hydrogenation, and hydrofinishing, unrefined, refined, re-refined oils or mixtures thereof. A more detailed description of unrefined, refined and re-refined oils is provided in International Publication WO2008/147704, paragraphs [0054] to [0056] (a similar disclosure is provided in US Patent Application 2010/197536, see [0072] to [0073]). A more detailed description of natural and synthetic lubricating oils is described in paragraphs [0058] to [0059] respectively of WO2008/147704 (a similar disclosure is provided in US Patent Application 2010/197536, see [0075] to [0076]). Synthetic oils may also be produced by Fischer-Tropsch reactions and typically may be hydroisomerised Fischer-Tropsch hydrocarbons or waxes. In one embodiment oils may be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid oils. 
         [0043]    Oils of lubricating viscosity may also be defined as specified in April 2008 version of “Appendix E—API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3 Sub-heading 1.3. “Base Stock Categories”. The API Guidelines are also summarised in U.S. Pat. No. 7,285,516 (see column 11, line 64 to column 12, line 10). 
         [0044]    In one embodiment the oil of lubricating viscosity may be an API Group I to IV mineral oil, an ester or a synthetic oil, or mixtures thereof. In one embodiment the oil of lubricating viscosity may be an API Group II, Group III, Group IV mineral oil, an ester or a synthetic oil, or mixtures thereof. 
         [0045]    The amount of the oil of lubricating viscosity present is typically the balance remaining after subtracting from 100 wt % the sum of the amount of the additives of the invention and the other performance additives. 
         [0046]    The lubricating composition may be in the form of a concentrate and/or a fully formulated lubricant. If the lubricating composition of the invention (comprising the additives disclosed herein) is in the form of a concentrate which may be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of the of these additives to the oil of lubricating viscosity and/or to diluent oil include the ranges of 1:99 to 99:1 by weight, or 80:20 to 10:90 by weight. Typically the lubricating composition of the invention comprises at least 50 wt %, or at least 60 wt %, or at least 70 wt %, or at least 80 wt % of an oil of lubricating viscosity. 
       Dispersant Viscosity Modifier 
       [0047]    The lubricating composition of the invention contains a dispersant viscosity modifier. The dispersant viscosity modifier may be present at 0.05 wt % to 1.5 wt %, or 0.1 wt % to 1 wt %, or 0.1 to 0.5 wt %. 
         [0048]    The dispersant viscosity modifier may include functionalised polyolefins, for example, ethylene-propylene copolymers that have been functionalised with an acylating agent such as maleic anhydride and an amine; polymethacrylates functionalised with an amine, or styrene-maleic anhydride copolymers reacted with an amine. More detailed description of dispersant viscosity modifiers are disclosed in International Publication WO2006/015130 or U.S. Pat. Nos. 4,863,623; 6,107,257; 6,107,258; 6,117,825; and U.S. Pat. No. 7,790,661. In one embodiment the dispersant viscosity modifier may include those described in U.S. Pat. No. 4,863,623 (see column 2, line 15 to column 3, line 52) or in International Publication WO2006/015130 (see page 2, paragraph [0008] and preparative examples are described paragraphs [0065] to [0073]). 
         [0049]    In one particular embodiment the dispersant viscosity modifier comprises an olefin copolymer further functionalised with a dispersant amine group. Typically, the olefin copolymer is an ethylene-propylene copolymer. 
         [0050]    The olefin copolymer has a number average molecular weight of 5000 to 100,000, or 7500 to 60,000, or 8000 to 45,000. 
         [0051]    The dispersant amine group may be prepared/derived from reacting the olefin copolymer (typically, a ethylene-propylene copolymer) with an acylating agent (typically maleic anhydride) and an aromatic amine having a primary or secondary amino group. Typically, the dispersant viscosity modifier may be an ethylene-propylene copolymer acylated with maleic anhydride and reacted with an aromatic amine. 
         [0052]    The formation of a dispersant viscosity modifier is well known in the art. The dispersant viscosity modifier may include for instance those described in U.S. Pat. No. 7,790,661 column 2, line 48 to column 10, line 38. 
         [0053]    In one embodiment the dispersant viscosity modifier may be prepared by grafting of an olefinic carboxylic acid acylating agent onto a polymer of 15 to 80 mole percent of ethylene, from 20 to 85 mole percent of C 3-10  α-monoolefin, and from 0 to 15 mole percent of non-conjugated diene or triene, said polymer having an average molecular weight ranging from 5000 to 500,000, and further reacting said grafted polymer with an amine (typically an aromatic amine). 
         [0054]    In another embodiment the dispersant viscosity modifier may be a reaction product of: (a) a polymer comprising carboxylic acid functionality or a reactive equivalent thereof, said polymer having a number average molecular weight of greater than 5,000; and (b) an amine component comprising at least one aromatic amine containing at least one amino group capable of condensing with said carboxylic acid functionality to provide a pendant group and at least one additional group comprising at least one nitrogen, oxygen, or sulfur atom, wherein said aromatic amine is selected from the group consisting of (i) a nitro-substituted aniline, (ii) an amine comprising two aromatic moieties linked by a —C(O)NR— group, a —C(O)O— group, an —O— group, an —N═N— group, or an —SO 2 — group where R is hydrogen or hydrocarbyl, one of said aromatic moieties bearing said condensable amino group, (iii) an aminoquinoline, (iv) an aminobenzimidazole, (v) an N,N-dialkylphenylenediamine, (vi), an aminodiphenylamine (also N,N-phenyldiamine), and (vii) a ring-substituted benzylamine. 
         [0055]    The aromatic amine of the dispersant viscosity modifier may also include those which can be represented by the general structure NH 2 —Ar or T-NH—Ar, where T may be alkyl or aromatic, Ar is an aromatic group, including nitrogen-containing or amino-substituted aromatic groups and Ar groups including any of the following structures: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    as well as multiple non-condensed or linked aromatic rings. In these and related structures, R v , R vi , and R vii  can be independently, among other groups disclosed herein, —H, —C 1-18  alkyl groups, nitro groups, —NH—Ar, —N═N—Ar, —NH—CO—Ar, —OOC—Ar, —OOC—C 1-18  alkyl, —COO—C 1-18  alkyl, —OH, —O—(CH 2 CH 2 —O) n C 1-18  alkyl groups, and —O—(CH 2 CH 2 O) n Ar (where n is 0 to 10). 
         [0056]    Aromatic amines include those amines wherein a carbon atom of the aromatic ring structure is attached directly to the amino nitrogen. The amines may be monoamines or polyamines. The aromatic ring will typically be a mononuclear aromatic ring (i.e., one derived from benzene) but can include fused aromatic rings, especially those derived from naphthalene. Examples of aromatic amines include aniline, N-alkylanilines such as N-methylaniline and N-butylaniline, di-(para-methylphenyl)amine, 4-aminodiphenylamine, N,N-dimethylphenylenediamine, naphthylamine, 4-(4-nitrophenylazo)aniline (disperse orange 3), sulphamethazine, 4-phenoxyaniline, 3-nitro aniline, 4-aminoacetanilide (N-(4-aminophenyl)acetamide)), 4-amino-2-hydroxy-benzoic acid phenyl ester (phenyl amino salicylate), N-(4-amino-phenyl)-benzamide, various benzylamines such as 2,5-dimethoxybenzylamine, 4-phenylazoaniline, and substituted versions of these. Other examples include para-ethoxyaniline, para-dodecylaniline, cyclohexyl-substituted naphthylamine, and thienyl-substituted aniline. Examples of other suitable aromatic amines include amino-substituted aromatic compounds and amines in which the amine nitrogen is a part of an aromatic ring, such as 3-aminoquinoline, 5-aminoquinoline, and 8-aminoquinoline. Also included are aromatic amines such as 2-aminobenzimidazole, which contains one secondary amino group attached directly to the aromatic ring and a primary amino group attached to the imidazole ring. Other amines include N-(4-anilinophenyl)-3-aminobutanamide or 3-amino propyl imidazole. Yet other amines include 2,5-dimethoxybenzylamine. 
         [0057]    Additional aromatic amines and related compounds are disclosed in U.S. Pat. Nos. 6,107,257 and 6,107,258; some of these include aminocarbazoles, benzoimidazoles, aminoindoles, aminopyrroles, amino-indazolinones, amino-perimidines, mercaptotriazoles, aminophenothiazines, aminopyridines, amino-pyrazines, aminopyrimidines, pyridines, pyrazines, pyrimidines, amino-thiadiazoles, aminothiothiadiazoles, and aminobenzotriaozles. Other suitable amines include 3-amino-N-(4-anilinophenyl)-N-isopropyl butanamide, and N-(4-anilinophenyl)-3-{(3-aminopropyl)-(cocoalkyl)amino}butanamide. Other aromatic amines which can be used include various aromatic amine dye intermediates containing multiple aromatic rings linked by, for example, amide structures. Examples include materials of the general structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    and isomeric variations thereof, where R viii  and R ix  are independently alkyl or alkoxy groups such as methyl, methoxy, or ethoxy. In one instance, R viii  and R ix  are both —OCH 3  and the material is known as Fast Blue RR [CAS#6268-05-9]. 
         [0058]    In another instance, R ix  is —OCH 3  and R viii  is —CH 3 , and the material is known as Fast Violet B [99-21-8]. When both R′ and R ix  are ethoxy, the material is Fast Blue BB [120-00-3]. U.S. Pat. No. 5,744,429 discloses other aromatic amine compounds, particularly aminoalkylphenothiazines. N-aromatic substituted acid amide compounds, such as those disclosed in U.S. Patent Application 2003/0030033 A1, may also be used for the purposes of this invention. Suitable aromatic amines include those in which the amine nitrogen is a substituent on an aromatic carboxyclic compound, that is, the nitrogen is not sp 2  hybridized within an aromatic ring. 
         [0059]    The aromatic amine may also comprise an amine formed by reacting an aldehyde with 4-aminodiphenylamine. The resultant amine may be described as an alkylene coupled amine having at least 4 aromatic groups, at least one —NH 2  functional group, and at least 2 secondary or tertiary amino groups. The aldehyde may be aliphatic, alicyclic or aromatic. The aliphatic aldehyde may be linear or branched. Examples of a suitable aromatic aldehyde include benzaldehyde or o-vanillin. Examples of an aliphatic aldehyde include formaldehyde (or a reactive equivalent thereof such as formalin or paraformaldehyde), ethanal or propanal. Typically the aldehyde may be formaldehyde or benzaldehyde. Alternatively, this aromatic amine may also be prepared by the methodology described in Berichte der Deutschen Chemischen Gesellschaft (1910), 43, 728-39. 
         [0060]    The aromatic amine formed by coupling an aldehyde and 4-aminodiphenylamine is described European Patent application EP 2 401 348 A in and may also be represented by the formula: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    wherein each variable
 
R 1  may be hydrogen or a C 1-5  alkyl group (typically hydrogen);
 
R 2  may be hydrogen or a C 1-5  alkyl group (typically hydrogen);
 
U may be an aliphatic, alicyclic or aromatic group, with the proviso that when U is aliphatic, the aliphatic group may be linear or branched alkylene group containing 1 to 5, or 1 to 2 carbon atoms; and
 
w may be 0 to 9 or 0 to 3 or 0 to 1 (typically 0).
 
         [0061]    In one embodiment the aromatic amine includes 4-aminodiphenylamine, aldehyde (typically formaldehyde) coupled 4-aminodiphenylamine, nitro-aniline (3-nitro-aniline), disperse orange-3 (DO3), or mixtures thereof. 
       Zinc Free Sulphur-Containing Antiwear Agent 
       [0062]    The lubricating composition of the invention contains a zinc free sulphur-containing antiwear agent. The zinc free sulphur-containing antiwear agent may be present at 0.01 wt % to 1.5 wt %, 0.05 wt % to 1 wt %, or 0.1 to 0.5 wt % of the lubricating composition. 
         [0063]    The zinc free sulphur-containing antiwear agent may be selected from the group consisting of a sulphurised olefin, a molybdenum compound, an amine salt of a (thio)phosphorus-containing compound, a thiadiazole, and mixtures thereof. 
         [0064]    In one embodiment the zinc free sulphur-containing antiwear agent may be a molybdenum compound. The molybdenum compound may be an antiwear agent or an antioxidant. The molybdenum compound may be selected from the group consisting of molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, amine salts of molybdenum compounds, and mixtures thereof. Typically the molybdenum compound may be molybdenum dithiocarbamate, or molybdenum dithiophosphate. 
         [0065]    The molybdenum compound may provide the lubricating composition with 0 to 1000 ppm, or 5 to 1000 ppm, or 10 to 750 ppm 5 ppm to 400 ppm, or 20 ppm to 350 ppm of molybdenum. Examples of molybdenum dithiocarbamates, which may be used as an antioxidant, include commercial materials sold under the trade names such as Vanlube 822™ and Molyvan™ A from R. T. Vanderbilt Co., Ltd., and Adeka Sakura-Lube™ S-100, S-165, S-600 and 525, or mixtures thereof. 
         [0066]    In another embodiment the zinc free sulphur-containing antiwear agent may be a sulphurised-olefin. The sulphurised olefin may be a polysulphide. 
         [0067]    In an embodiment the sulphurised-olefin includes dihydrocarbyl polysulphides; sulphurised olefins; sulphurised fatty acid esters of both natural and synthetic origins; trithiones; sulphurised thienyl derivatives; sulphurised terpenes; sulphurised oligomers of C2-C8 monoolefins; and sulphurised Diels-Alder adducts such as those disclosed in U.S. Pat. No. Re 27,331. Specific examples include sulphurised polyisobutene, sulphurised isobutylene, sulphurised diisobutylene, sulphurised triisobutylene, dicyclohexyl polysulphide, diphenyl polysulphide, dibenzyl polysulphide, dinonyl polysulphide, and mixtures of di-tert-butyl polysulphide such as mixtures of di-tert-butyl trisulphide, di-tert-butyl tetrasulphide and di-tert-butyl pentasulphide, among others. Combinations of such categories of sulphur-containing antiwear and/or extreme pressure agents may also be used, such as a combination of sulphurised isobutylene and di-tert-butyl trisulphide, a combination of sulphurised isobutylene and dinonyl trisulphide, a combination of sulphurised tall oil and dibenzyl polysulphide. 
         [0068]    In a further embodiment at least 50 wt % of the polysulphide molecules are a mixture of tri- or tetra-sulphides. In other embodiments at least 55 wt %, or at least 60 wt % of the polysulphide molecules are a mixture of tri- or tetra-sulphides. 
         [0069]    The polysulphide includes a sulphurised organic polysulphide from oils, fatty acids or ester (such as ester-containing sulphurised olefin), olefins or polyolefins. 
         [0070]    Oils which may be sulfurized include natural or synthetic oils such as mineral oils, lard oil, carboxylate esters derived from aliphatic alcohols and fatty acids or aliphatic carboxylic acids (e.g., myristyl oleate and oleyl oleate), and synthetic unsaturated esters or glycerides. 
         [0071]    Fatty acids include those that contain 8 to 30, or 12 to 24 carbon atoms. Examples of fatty acids include oleic, linoleic, linolenic, and tall oil. Sulphurised fatty acid esters prepared from mixed unsaturated fatty acid esters such as are obtained from animal fats and vegetable oils, including tall oil, linseed oil, soybean oil, rapeseed oil, and fish oil. 
         [0072]    The polysulphide includes olefins derived from a wide range of alkenes. The alkenes typically have one or more double bonds. The olefins in one embodiment contain 3 to 30 carbon atoms. In other embodiments, olefins contain 3 to 16, or 3 to 9 carbon atoms. In one embodiment the sulphurised olefin includes an olefin derived from propylene, isobutylene, pentene or mixtures thereof. 
         [0073]    In another embodiment the polysulphide comprises a polyolefin derived from polymerising by known techniques, an olefin as described above. 
         [0074]    In still another embodiment the polysulphide includes dibutyl tetrasulphide, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised dicyclopentadiene, sulphurised terpene, and sulphurised Diels-Alder adducts. 
         [0075]    In a further embodiment the sulphurised olefin may be an ester-containing sulphurised olefin. The ester-containing sulphurised olefin may include a sulphurised 4-carbobutoxy cyclohexene. 
         [0076]    In a still further embodiment the zinc free sulphur-containing antiwear agent may be a thiadiazole compound. Examples of a thiadiazole include 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof, a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, a hydrocarbylthio-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof. The oligomers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically form by forming a sulphur-sulphur bond between 2,5-dimercapto-1,3,4-thiadiazole units to form oligomers of two or more of said thiadiazole units. These thiadiazole compounds may also be used in the post treatment of dispersants as mentioned below in the formation of a dimercaptothiadiazole derivative of a polyisobutylene succinimide. 
         [0077]    Examples of a suitable thiadiazole compound include at least one of a dimercaptothiadiazole, 2,5-dimercapto-[1,3,4]-thiadiazole, 3,5-dimercapto-[1,2,4]-thiadiazole, 3,4-dimercapto-[1,2,5]-thiadiazole, or 4-5-dimercapto-[1,2,3]-thiadiazole. Typically readily available materials such as 2,5-dimercapto-1,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole or a hydrocarbylthio-substituted 2,5-dimercapto-1,3,4-thiadiazole are commonly utilised. 
         [0078]    In one embodiment the zinc free sulphur-containing antiwear agent may be an amine salt of a (thio)phosphorus-containing compound. The an amine salt of a (thio)phosphorus-containing compound may be an amine salt of a phosphate hydrocarbon ester (i.e., an amine salt of a hydrocarbon ester of phosphoric acid). The amine salt of a phosphate hydrocarbon ester may be derived from an amine salt of a phosphate. The amine salt of the phosphate hydrocarbon ester may be represented by the formula: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    wherein
 
R 3  and R 4  may be independently hydrogen or hydrocarbon typically containing 4 to 40, or 6 to 30, or 6 to 18, or 8 to 18 carbon atoms, with the proviso that at least one is a hydrocarbon group; and
 
R 5 , R 6 , R 7  and R 8  may be independently hydrogen or a hydrocarbyl group, with the proviso that at least one is a hydrocarbyl group.
 
         [0079]    The hydrocarbon groups of R 3  and/or R 4  may be linear, branched, or cyclic. 
         [0080]    The amine salt of a phosphate hydrocarbon ester may be prepared as is described in U.S. Pat. No. 6,468,946. Column 10, lines 15 to 63 describes phosphoric acid esters formed by reaction of phosphorus compounds, followed by reaction with an amine to form an amine salt of a phosphate hydrocarbon ester. Column 10, line 64, to column 12, line 23, describes preparative examples of reactions between phosphorus pentoxide with an alcohol (having 4 to 13 carbon atoms), followed by a reaction with an amine (typically Primene®81-R) to form an amine salt of a phosphate hydrocarbon ester. 
         [0081]    The amine salt of a (thio)phosphorus-containing compound may also be a compound described in European patent applications EP 2 318 493 A, and 2 113 023 A. Disclosed in both EP applications is a sulphur-free amine salt of a phosphorus compound obtained/obtainable by a process comprising: reacting an amine with either (i) a hydroxy-substituted di-ester of phosphoric acid, or (ii) a phosphorylated hydroxy-substituted di- or tri-ester of phosphoric acid, and represented by Formula (1) and (1a) in both publications. 
         [0082]    The lubricating composition may comprise 0.01 wt % to 1.5 wt % sulphurised olefin, 0.05 wt % to 1.5 wt %, an olefin copolymer further functionalised with a dispersant amine group. 
         [0083]    The lubricating composition may further comprise a mobybdenum-containing compound selected from the group consisting essentially of molybdenum dithiocarbamate, and molybdenum dithiophosphate (typically molybdenum dithiocarbamate) present in an amount ranging from 0.01 to 0.75 wt %, or 0.05 wt % to 0.5 wt %, or 0.1 wt % to 0.4 wt %. 
         [0084]    The lubricating composition may comprise 0.01 wt % to 0.75 wt % molybdenum dithiocarbamate, 0.05 wt % to 1.5 wt %, an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
         [0085]    The lubricating composition may comprise 0.01 wt % to 1.5 wt % sulphurised olefin, 0.01 wt % to 0.75 wt % molybdenum dithiocarbamate, 0.05 wt % to 1.5 wt %, an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
       Other Performance Additives 
       [0086]    A lubricating composition may be prepared by adding the product of the process described herein to an oil of lubricating viscosity, optionally in the presence of other performance additives (as described herein below). 
         [0087]    The lubricating composition of the invention optionally comprises other performance additives. The other performance additives include at least one of metal deactivators, viscosity modifiers, detergents, friction modifiers, antiwear agents, corrosion inhibitors, dispersants, dispersant viscosity modifiers, extreme pressure agents, antioxidants, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents and mixtures thereof. Typically, fully-formulated lubricating oil will contain one or more of these performance additives. 
         [0088]    In one embodiment the invention provides a lubricating composition further comprising an overbased metal-containing detergent. The metal of the metal-containing detergent may be zinc, sodium, calcium, barium, or magnesium. Typically the metal of the metal-containing detergent may be sodium, calcium, or magnesium. 
         [0089]    The overbased metal-containing detergent may be selected from the group consisting of non-sulphur containing phenates, sulphur containing phenates, sulphonates, salixarates, salicylates, and mixtures thereof, or borated equivalents thereof. The overbased detergent may be borated with a borating agent such as boric acid. 
         [0090]    The overbased metal-containing detergent may also include “hybrid” detergents formed with mixed surfactant systems including phenate and/or sulphonate components, e.g. phenate/salicylates, sulphonate/phenates, sulphonate/salicylates, sulphonates/phenates/salicylates, as described; for example, in U.S. Pat. Nos. 6,429,178; 6,429,179; 6,153,565; and 6,281,179. Where, for example, a hybrid sulphonate/phenate detergent is employed, the hybrid detergent would be considered equivalent to amounts of distinct phenate and sulphonate detergents introducing like amounts of phenate and sulphonate soaps, respectively. 
         [0091]    Typically, an overbased metal-containing detergent may be a zinc, sodium, calcium or magnesium salt of a phenate, sulphur containing phenate, sulphonate, salixarate or salicylate. Overbased salixarates, phenates and salicylates typically have a total base number of 180 to 450 TBN. Overbased sulphonates typically have a total base number of 250 to 600, or 300 to 500. Overbased detergents are known in the art. In one embodiment the sulphonate detergent may be a predominantly linear alkylbenzene sulphonate detergent having a metal ratio of at least 8 as is described in paragraphs [0026] to [0037] of US Patent Application 2005065045 (and granted as U.S. Pat. No. 7,407,919). The predominantly linear alkylbenzene sulphonate detergent may be particularly useful for assisting in improving fuel economy. 
         [0092]    Typically, the overbased metal-containing detergent may be a calcium or magnesium an overbased detergent. 
         [0093]    Overbased detergents are known in the art. Overbased materials, otherwise referred to as overbased or superbased salts, are generally single phase, homogeneous Newtonian systems characterized by a metal content in of that which would be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter such as a calcium chloride, acetic acid, phenol or alcohol. The acidic organic material will normally have a sufficient number of carbon atoms to provide a degree of solubility in oil. The amount of “excess” metal (stoichiometrically) is commonly expressed in terms of metal ratio. The term “metal ratio” is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound. A neutral metal salt has a metal ratio of one. A salt having 3.5 times as much metal as present in a normal salt will have metal excess of 3.5 equivalents, or a ratio of 4.5. The term “metal ratio is also explained in standard textbook entitled “Chemistry and Technology of Lubricants”, Third Edition, Edited by R. M. Mortier and S. T. Orszulik, Copyright 2010, page 219, sub-heading 7.25. 
         [0094]    In another embodiment the lubricating composition further comprises a calcium sulphonate overbased detergent and a calcium phenate overbased detergent in an amount such that the sulphated ash content is 1000 ppm or less (such as 100 ppm to 1000 ppm, or 300 ppm to 900 ppm). 
         [0095]    The lubricating composition in a further embodiment comprises an antioxidant, wherein the antioxidant comprises a phenolic or an aminic antioxidant or mixtures thereof. The antioxidants include diarylamines, alkylated diarylamines, hindered phenols, or mixtures thereof. When present the antioxidant is present at 0.1 wt % to 3 wt %, or 0.5 wt % to 2.75 wt %, or 1 wt % to 2.5 wt % of the lubricating composition. 
         [0096]    The diarylamine or alkylated diarylamine may be a phenyl-α-naphthylamine (PANA), an alkylated diphenylamine, or an alkylated phenylnapthylamine, or mixtures thereof. The alkylated diphenylamine may include di-nonylated diphenylamine, nonyl diphenylamine, octyl diphenylamine, di-octylated diphenylamine, di-decylated diphenylamine, decyl diphenylamine and mixtures thereof. In one embodiment the diphenylamine may include nonyl diphenylamine, dinonyl diphenylamine, octyl diphenylamine, dioctyl diphenylamine, or mixtures thereof. In another embodiment the alkylated diphenylamine may include nonyl diphenylamine, or dinonyl diphenylamine. The alkylated diarylamine may include octyl, di-octyl, nonyl, di-nonyl, decyl or di-decyl phenylnapthylamines. 
         [0097]    The hindered phenol antioxidant often contains a secondary butyl and/or a tertiary butyl group as a sterically hindering group. The phenol group may be further substituted with a hydrocarbyl group (typically linear or branched alkyl) and/or a bridging group linking to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2, 6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment the hindered phenol antioxidant may be an ester and may include, e.g., Irganox™ L-135 from Ciba. A more detailed description of suitable ester-containing hindered phenol antioxidant chemistry is found in U.S. Pat. No. 6,559,105. 
         [0098]    The lubricating composition may in a further embodiment include a dispersant, or mixtures thereof. The dispersant may be a succinimide dispersant, a Mannich dispersant, a succinamide dispersant, a polyolefin succinic acid ester, amide, or ester-amide, or mixtures thereof. In one embodiment the dispersant may be present as a single dispersant. In one embodiment the dispersant may be present as a mixture of two or three different dispersants, wherein at least one may be a succinimide dispersant. 
         [0099]    The succinimide dispersant may be derived from an aliphatic polyamine, or mixtures thereof. The aliphatic polyamine may be aliphatic polyamine such as an ethylenepolyamine, a propylenepolyamine, a butylenepolyamine, or mixtures thereof. In one embodiment the aliphatic polyamine may be ethylenepolyamine. In one embodiment the aliphatic polyamine may be selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetramine, tetra-ethylenepentamine, pentaethylenehexamine, polyamine still bottoms, and mixtures thereof. 
         [0100]    In one embodiment the dispersant may be a polyolefin succinic acid ester, amide, or ester-amide. For instance, a polyolefin succinic acid ester may be a polyisobutylene succinic acid ester of pentaerythritol, or mixtures thereof. A polyolefin succinic acid ester-amide may be a polyisobutylene succinic acid reacted with an alcohol (such as pentaerythritol) and a polyamine as described above. 
         [0101]    The dispersant may be an N-substituted long chain alkenyl succinimide. An example of an N-substituted long chain alkenyl succinimide is polyisobutylene succinimide. Typically the polyisobutylene from which polyisobutylene succinic anhydride is derived has a number average molecular weight of 350 to 5000, or 550 to 3000 or 750 to 2500. Succinimide dispersants and their preparation are disclosed, for instance in U.S. Pat. Nos. 3,172,892, 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re 26,433, and 6,165,235, 7,238,650 and EP Patent Application 0 355 895 A. 
         [0102]    The dispersants may also be post-treated by conventional methods by a reaction with any of a variety of agents. Among these are boron compounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles, carbon disulphide, aldehydes, ketones, carboxylic acids such as terephthalic acid, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, and phosphorus compounds. In one embodiment the post-treated dispersant is borated. In one embodiment the post-treated dispersant is reacted with dimercaptothiadiazoles. In one embodiment the post-treated dispersant is reacted with phosphoric or phosphorous acid. In one embodiment the post-treated dispersant is reacted with terephthalic acid and boric acid (as described in US Patent Application US2009/0054278. 
         [0103]    When present, the dispersant may be present at 0.01 wt % to 20 wt %, or 0.1 wt % to 15 wt %, or 0.1 wt % to 10 wt %, or 1 wt % to 6 wt %, or 1 to 3 wt % of the lubricating composition. 
         [0104]    In one embodiment the friction modifier may be selected from the group consisting of long chain fatty acid derivatives of amines, long chain fatty esters, or derivatives of long chain fatty epoxides; fatty imidazolines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fatty glycolates; and fatty glycolamides. The friction modifier may be present at 0 wt % to 6 wt %, or 0.01 wt % to 4 wt %, or 0.05 wt % to 2 wt %, or 0.1 wt % to 2 wt % of the lubricating composition. 
         [0105]    As used herein the term “fatty alkyl” or “fatty” in relation to friction modifiers means a carbon chain having 10 to 22 carbon atoms, typically a straight carbon chain. 
         [0106]    Examples of suitable friction modifiers include long chain fatty acid derivatives of amines, fatty esters, or fatty epoxides; fatty imidazolines such as condensation products of carboxylic acids and polyalkylene-polyamines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fatty phosphonates; fatty phosphites; borated phospholipids, borated fatty epoxides; glycerol esters; borated glycerol esters; fatty amines; alkoxylated fatty amines; borated alkoxylated fatty amines; hydroxyl and polyhydroxy fatty amines including tertiary hydroxy fatty amines; hydroxy alkyl amides; metal salts of fatty acids; metal salts of alkyl salicylates; fatty oxazolines; fatty ethoxylated alcohols; condensation products of carboxylic acids and polyalkylene polyamines; or reaction products from fatty carboxylic acids with guanidine, aminoguanidine, urea, or thiourea and salts thereof. 
         [0107]    Friction modifiers may also encompass materials such as sulphurised fatty compounds and olefins, molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, sunflower oil or soybean oil monoester of a polyol and an aliphatic carboxylic acid. 
         [0108]    In another embodiment the friction modifier may be a long chain fatty acid ester. In another embodiment the long chain fatty acid ester may be a mono-ester and in another embodiment the long chain fatty acid ester may be a triglyceride. 
         [0109]    The lubricating composition optionally further includes at least one antiwear agent. Examples of suitable antiwear agents include titanium compounds, tartrates, tartrimides, oil soluble amine salts of phosphorus compounds, sulphurised olefins, metal dihydrocarbyldithiophosphates (such as zinc dialkyldithiophosphates), phosphites (such as dibutyl phosphite), phosphonates, thiocarbamate-containing compounds, such as thiocarbamate esters, thiocarbamate amides, thiocarbamic ethers, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulphides. The antiwear agent may in one embodiment include a tartrate, or tartrimide as disclosed in International Publication WO 2006/044411 or Canadian Patent CA 1 183 125. The tartrate or tartrimide may contain alkyl-ester groups, where the sum of carbon atoms on the alkyl groups is at least 8. The antiwear agent may in one embodiment include a citrate as is disclosed in US Patent Application 20050198894. 
         [0110]    Another class of additives includes oil-soluble titanium compounds as disclosed in U.S. Pat. No. 7,727,943 and US2006/0014651. The oil-soluble titanium compounds may function as antiwear agents, friction modifiers, antioxidants, deposit control additives, or more than one of these functions. In one embodiment the oil soluble titanium compound is a titanium (IV) alkoxide. The titanium alkoxide is formed from a monohydric alcohol, a polyol or mixtures thereof. The monohydric alkoxides may have 2 to 16, or 3 to 10 carbon atoms. In one embodiment, the titanium alkoxide is titanium (IV) isopropoxide. In one embodiment, the titanium alkoxide is titanium (IV) 2-ethylhexoxide. In one embodiment, the titanium compound comprises the alkoxide of a vicinal 1,2-diol or polyol. In one embodiment, the 1,2-vicinal diol comprises a fatty acid mono-ester of glycerol, often the fatty acid is oleic acid. 
         [0111]    In one embodiment, the oil soluble titanium compound is a titanium carboxylate. In a further embodiment the titanium (IV) carboxylate is titanium neodecanoate. 
         [0112]    The lubricating composition may in one embodiment further include a phosphorus-containing antiwear agent. Typically the phosphorus-containing antiwear agent may be a zinc dialkyldithiophosphate, phosphite, phosphate, phosphonate, and ammonium phosphate salts, or mixtures thereof. Zinc dialkyldithiophosphates are known in the art. The antiwear agent may be present at 0 wt % to 3 wt %, or 0.1 wt % to 1.5 wt %, or 0.5 wt % to 0.9 wt % of the lubricating composition. 
         [0113]    Extreme Pressure (EP) agents that are soluble in the oil include sulphur- and chlorosulphur-containing EP agents, dimercaptothiadiazole or CS 2  derivatives of dispersants (typically succinimide dispersants), derivative of chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples of such EP agents include chlorinated wax; sulphurised olefins (such as sulphurised isobutylene), a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof, organic sulphides and polysulphides such as dibenzyl-disulphide, bis-(chlorobenzyl) disulphide, dibutyl tetrasulphide, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene, and sulphurised Diels-Alder adducts; phosphosulphurised hydrocarbons such as the reaction product of phosphorus sulphide with turpentine or methyl oleate; phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite; metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptyl-phenol diacid; amine salts of alkyl and dialkylphosphoric acids or derivatives including, for example, the amine salt of a reaction product of a dialkyl-dithiophosphoric acid with propylene oxide and subsequently followed by a further reaction with P 2 O 5 ; and mixtures thereof (as described in U.S. Pat. No. 3,197,405). 
         [0114]    Foam inhibitors that may be useful in the compositions of the invention include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate; demulsifiers including fluorinated polysiloxanes, trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers. 
         [0115]    Pour point depressants that may be useful in the compositions of the invention include polyalphaolefins, esters of maleic anhydride-styrene copolymers, poly(meth)acrylates, polyacrylates or polyacrylamides. 
         [0116]    Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof. 
         [0117]    Metal deactivators include derivatives of benzotriazoles (typically tolyltriazole), 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles. The metal deactivators may also be described as corrosion inhibitors. 
         [0118]    Seal swell agents include sulfolene derivatives Exxon Necton-37™ (FN 1380) and Exxon Mineral Seal Oil™ (FN 3200). 
       INDUSTRIAL APPLICATION 
       [0119]    The internal combustion engine may be a 4-stroke engine. The internal combustion engine may or may not have an Exhaust Gas Recirculation system. The internal combustion engine may be fitted with an emission control system or a turbocharger. Examples of the emission control system include diesel particulate filters (DPF), or systems employing selective catalytic reduction (SCR). 
         [0120]    The sulphur content of the lubricating composition may be 1 wt % or less, or 0.8 wt % or less, or 0.5 wt % or less, or 0.3 wt % or less. In one embodiment the sulphur content may be in the range of 0.001 wt % to 0.5 wt %, or 0.01 wt % to 0.3 wt %. The phosphorus content may be 0.2 wt % or less, or 0.12 wt % or less, or 0.1 wt % or less, or 0.085 wt % or less, or 0.08 wt % or less, or even 0.06 wt % or less, 0.055 wt % or less, or 0.05 wt % or less. In one embodiment the phosphorus content may be 0.04 wt % to 0.12 wt %. In one embodiment the phosphorus content may be 100 ppm to 1000 ppm, or 200 ppm to 600 ppm. The total sulphated ash content may be 0.3 wt % to 1.2 wt %, or 0.5 wt % to 1.1 wt % of the lubricating composition. In one embodiment the sulphated ash content may be 0.5 wt % to 1.1 wt % of the lubricating composition. 
         [0121]    In one embodiment the lubricating composition may be characterised as having at least one of (i) a sulphur content of 0.5 wt % or less, (ii) a phosphorus content of 0.12 wt % or less, and (iii) a sulphated ash content of 0.5 wt % to 1.1 wt % of the lubricating composition. 
         [0122]    The lubricating composition may have a SAE viscosity grade of XW-Y, wherein X may be 0, 5, 10, or 15; and Y may be 20, 30, or 40. 
         [0123]    The following examples provide illustrations of the invention. These examples are non-exhaustive and are not intended to limit the scope of the invention. 
       EXAMPLES 
     Example 1 
       [0124]    (EX1): is 0W-30 lubricating composition comprising at least 74 wt % of an API Group III/Group IV base oil mixture, molybdenum dithiocarbamate present in an amount to deliver about 300 ppm of molybdenum, 0.33 wt % of a dispersant viscosity modifier prepared by reacting ethylene-propylene copolymer with maleic anhydride and reacting it with 3-nitroaniline and dimethylaminopropylamine (DMAPA). The lubricating composition further contains a polyisobutylene succinimide, 2.1 wt % of a mixture of aminic and phenolic antioxidants, 0.65 wt % of zinc dialkyldithiophosphate, 0.1 wt % of calcium overbased sulphonate, 1 wt % calcium overbased phenate, and 0.6 wt % of a viscosity modifier. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
       Example 2 
       [0125]    (EX2): is a 0W-30 lubricating composition comprising at least 74 wt % of an API Group III/Group IV base oil mixture, 0.3 wt % of a sulphurised olefin, 0.33 wt % of a dispersant viscosity modifier prepared by reacting ethylene-propylene copolymer with maleic anhydride and reacting it with 3-nitroaniline and dimethylaminopropylamine (DMAPA). The lubricating composition further contains a polyisobutylene succinimide, 2.1 wt % of a mixture of aminic and phenolic antioxidants, 0.65 wt % of zinc dialkyldithiophosphate, 0.1 wt % of calcium overbased sulphonate, 1 wt % calcium overbased phenate, and 0.6 wt % of a viscosity modifier. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
       Comparative Example 1 
       [0126]    (CE1): is similar to EX1 except the lubricant does not contain a molybdenum dithiocarbamate, a dispersant viscosity modifier, or a sulphurised-olefin. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
       Comparative Example 2 
       [0127]    (CE2): is similar to EX1 except it contains a molybdenum dithiocarbamate present in an amount to deliver 500 ppm of molybdenum, and no dispersant viscosity modifier, or sulphurised-olefin. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
       Comparative Example 3 
       [0128]    (CE3): is similar to EX2 except it contains 0.2 wt % of sulphurised olefin and does not contain a molybdenum dithiocarbamate, or a dispersant viscosity modifier. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
       Comparative Example 4 
       [0129]    (CE4): is similar to EX1 except it does not contain molybdenum dithiocarbamate. The lubricating composition has sulphur-content of less than 0.3 wt %, a phosphorus content of about 600 ppm, and a sulphated ash content of 0.55 wt %. 
         [0130]    Lubricating Examples EX1, EX2, and CE1 to CE4 are evaluated by DW10 engine test protocol run by APL in 2011-2013. The results obtained for the testing are presented in the following table. Typically better results are obtained for samples with a rating of 7 or more, and the test specifies a minimum pass rating of 7. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Lubricant Example 
                 Rating 
               
               
                   
                   
               
             
             
               
                   
                 CE1 
                 5.75 
               
               
                   
                 CE2 
                 6.43 
               
               
                   
                 CE3 
                 5.89 
               
               
                   
                 CE4 
                 6.41 
               
               
                   
                 EX1 
                 8.52 
               
               
                   
                 EX2 
                 7.46 
               
               
                   
                   
               
             
          
         
       
     
         [0131]    The results obtained from the DW10 lash adjuster test indicate that a lubricating composition defined by the present invention passes the test, and lubricating compositions outside the scope of the claimed invention fail the test. 
         [0132]    It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. The products formed thereby, including the products formed upon employing lubricant composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses lubricant composition prepared by admixing the components described above. 
         [0133]    Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about.” Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention may be used together with ranges or amounts for any of the other elements. 
         [0134]    As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: hydrocarbon substituents, including aliphatic, alicyclic, and aromatic substituents; substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent; and hetero substituents, that is, substituents which similarly have a predominantly hydrocarbon character but contain other than carbon in a ring or chain. A more detailed definition of the term “hydrocarbyl substituent” or “hydrocarbyl group” is described in paragraphs [0118] to [0119] of International Publication WO2008147704, or a similar definition in paragraphs [0137] to [0141] of published application US 2010-0197536. 
         [0135]    As used herein the detergent total base number (TBN) may be measure by ASTM D2896. 
         [0136]    While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.