Lubricating oil compositions

A lubricating oil composition for internal combustion engines comprises: (A) a major amount of a basestock of lubricating viscosity containing from greater than 35 to less than 70 mass % of one or more PAO's, the balance preferably being one or more Group I basestocks as defined in API 1509; and (B) two or more additive components such as an ashless dispersant and a metal detergent.

This invention relates to lubricating oil compositions for internal 
combustion engines for use in the crankcase thereof. 
Manufacturers of internal combustion engines are interested in increasing 
the period, expressed in terms of mileage or time, between required 
changes of crankcase lubricant in use in their engines in motor vehicles. 
Lubricant formulators are addressing the problem and tests have been 
devised that are a measure of the lubricant's ability to remain in use in 
the crankcase for longer--in terms of mileage or time--than hitherto. Such 
tests may be referred to as "long drain suitability tests". An example of 
such a test is the VW PV 1449 test for gasoline engines. 
The present invention is concerned with improving performance in "long 
drain suitability tests" without the need to use expensive, specialised 
formulations, by providing a defined basestock in a lubricating oil 
composition. 
Basestocks, sometimes referred to as base oils, used in lubricating oil 
compositions may comprise synthetic or natural oils used as crankcase 
lubricating oils for spark-ignited and compression-ignited engines. The 
lubricating oil basestock conveniently has a kinematic viscosity of 2.5 to 
12 mm.sup.2 /s and preferably 2.5 to 9 mm.sup.2 /s at 100.degree. C. The 
viscosity characteristic of a basestock is typically expressed by the 
neutral number of the oil (e.g. S150N) with a higher neutral number being 
associated with a higher viscosity at a given temperature. This number is 
defined as the viscosity of the basestock at 40.degree. C. measured in 
Saybolt Universal Seconds. The average basestock neutral number (ave. 
BSNN) of a blend of straight cuts may be determined according to the 
following formula: 
##EQU1## 
where BSRn=basestock ratio for basestock n =(wt % basestock n/wt % total 
basestock in oil).times.100% 
BSNNn=basestock neutral number for basestock n 
Basestocks with lower solvent neutral numbers are used for lower viscosity 
grades. For example, a typical basestock will have a BSNN between 90 and 
180. 
GB-A-2 292 747 describes automotive crankcase lubricants containing a polar 
dispersant and a base oil containing from 20 to 70% of PAO 
(polyalphaolefin) oil, and specifically exemplifies 35 and 20% and prefers 
15 to 25%. It states that the lubricants preferably include a detergent. 
It further states that the lubricants are compatible with fluorocarbon and 
nitrile material used in engine seals. 
However, a problem with the lubricants described in GB-A-2 292 747 is that, 
when they contain PAO in the percentages specified therein, they would 
either give rise to high viscosity increase in engine tests, as evidenced 
herein, at the lower percentages of PAO described or become expensive at 
the high percentage of PAO described. 
The present invention is concerned with use of intermediate quantities of 
PAO to meet the aforesaid problem. 
Thus, a first aspect of the invention is a lubricating oil composition for 
an internal combustion engine comprising: 
(A) a major amount of a basestock of lubricating viscosity containing from 
greater than 35 to less than 70, such as from 37 to 68, preferably from 40 
to 60, mass % of one or more Group IV basestocks; and 
(B) two or more additive components. 
Preferably, the balance of the basestock is one or more basestocks selected 
from Group I basestocks. Groups I and IV are defined below. 
Preferably the basestock contains from greater than 40 to less than 60, 
such as 42 to 58, preferably 45 to 55, mass % of said one or more Group IV 
basestocks. 
A second aspect of the invention is a method of making a lubricating oil 
composition comprising blending (A) and (B), each of (A) and (B) being as 
defined in the first aspect. 
A third aspect of the invention is a method of operating an internal 
combustion engine, such as a spark-ignited engine, comprising lubricating 
the engine with a lubricating oil composition of the first aspect or made 
by the method of the second aspect. 
A fourth aspect of the invention is a method for increasing the period 
between crankcase lubricant changes in a spark-ignited engine comprising 
treating moving surfaces thereof with a lubricating oil composition 
comprising, or made by blending, 
(A) a major amount of a basestock of lubricating viscosity containing from 
25 to 80, such as 25 to 70, mass % of one or more Group IV basestocks, as 
defined herein, or of a mixture thereof; and 
(B) two or more additive components, such as of the first aspect or made by 
the method of the second aspect. 
The features of the invention will now be discussed in further detail as 
follows. 
(A) BASESTOCK 
The basestock conveniently has a viscosity of 2 to 20 such as 2.5 to 12 cSt 
at 100.degree. C., advantageously 2.5 to 9 cSt at 100.degree. C., 
preferably 3 to 7 cSt at 100.degree. C. 
Basestocks may be made using a variety of different processes including but 
not limited to distillation, solvent refining, hydrogen processing, 
oligomerisation, esterification, and rerefining. API 1509 "Engine Oil 
Licensing and Certification System" Fourteenth Edition, December 1996 
states that all basestocks are divided into five general categories: 
Group I contain less than 90% saturates and/or greater than 0.03% sulfur 
and have a viscosity index greater than or equal to 80 and less than 120; 
Group II contain greater than or equal to 90% saturates and less than or 
equal to 0.03% sulfur and have a viscosity index greater than or equal to 
80 and less than 120; 
Group III contain greater than or equal to 90% saturates and less than or 
equal to 0.03% sulfur and have a viscosity index greater than or equal to 
120; 
Group IV are polyalphaolefins (PAO); and 
Group V include all other basestocks not included in Group I, II, III or 
IV. 
The test methods used in defining the above groups are ASTM D2007 for 
saturates; ASTM D2270 for viscosity index; and one of ASTM D2622, 4294, 
4927 and 3120 for sulfur. 
Group IV basestocks, i.e. polyalphaolefins (PAO) include hydrogenated 
oligomers of an alpha-olefin, the most important methods of 
oligomerisation being free radical processes, Ziegler catalysis, and 
cationic, Friedel-Crafts catalysis. 
The polyalphaolefins typically have viscosities in the range of 2 to 20 cSt 
at 100.degree. C., preferably 4 to 8 cSt at 100.degree. C. They may, for 
example, be oligomers of branched or straight chain alpha-olefins having 
from 2 to 16 carbon atoms, specific examples being polypropenes, 
polyisobutenes, poly-1-butenes, poly-1-hexenes, poly-1-octenes and 
poly-1-decene. Included are homopolymers, interpolymers and mixtures. 
PAO's are described in "Chemistry and Technology of Lubricants" edited by 
R. M. Mortier and S. T. Orszulik, published by Blackie (Glasgow) and VCH 
Publishers Inc. N.Y. (1992): Ch 2 Synthetic base fluids. 
Regarding the balance of the basestock referred to above, a "Group I 
basestock" also includes a Group I basestock with which basestock(s) from 
one or more other groups is or are admixed, provided that the resulting 
admixture has characteristics falling within those specified above for 
Group I basestocks. 
(B) ADDITIVE COMPONENTS 
Examples are as follows: 
ASHLESS DISPERSANTS 
Examples are high molecular weight ashless dispersants include the range of 
ashless dispersants known as effective for adding to lubricant oils for 
the purpose of reducing the formation of deposits in gasoline or diesel 
engines. By "high molecular weight" is meant having a number average 
molecular weight of between 700 and 5000 such as between 1300 and 1400. A 
wide variety of such compounds is available, as now described in more 
detail. 
The ashless dispersant comprises an oil soluble polymeric hydrocarbon 
backbone having functional groups that are capable of associating with 
particles to be dispersed. Typically, the dispersants comprise amine, 
alcohol, amide, or ester polar moieties attached to the polymer backbone 
often via a bridging group. The ashless dispersant may be, for example, 
selected from oil soluble salts, esters, amino-esters, amides, imides, and 
oxazolines of long chain hydrocarbon substituted mono and dicarboxylic 
acids or their anhydrides; thiocarboxylate derivatives of long chain 
hydrocarbons; long chain aliphatic hydrocarbons having a polyamine 
attached directly thereto; and Mannich condensation products formed by 
condensing a long chain substituted phenol with formaldehyde and 
polyalkylene polyamine. 
Processes for reacting polymeric hydrocarbons with unsaturated carboxylic 
acids, anhydrides or esters and the preparation of derivatives from those 
compounds are disclosed in U.S. Pat. Nos. 3,087,936, 3,172,892, 3,215,707, 
3,231,587, 3,231,587, 3,272,746, 3,275,554, 3,381,022, 3,442,808, 356,804, 
3,912,764, 4,110,349, 4,234,435 and GB-A-1440219. 
A class of ashless dispersants comprising ethylene alpha-olefin copolymers 
and alpha-olefin homo- and copolymers prepared using new metallocene 
catalyst chemistry, which may have a high degree (e.g. &gt;30%) of terminal 
vinylidene unsaturation is described in U.S. Pat. Nos. 5,128,056, 
5,151,204, 5,200,103, 5,225,092, 5,266,223, 5,334,775; WO-A-94/19436, 
94/13709; and EP-A440506, 513157, 513211. These dispersants are described 
as having superior viscometric properties as expressed in a ratio of CCS 
viscosity to kV 100.degree. C. 
The term "alpha-olefin" is used herein to denote an olefin of the formula 
##STR1## 
wherein R' is preferably a C.sub.1 -C.sub.18 alkyl group. The requirement 
for terminal vinylidene unsaturation refers to the presence in the polymer 
of the following structure: 
##STR2## 
wherein Poly is the polymer chain and R is typically a C.sub.1 -C.sub.18 
alkyl group, typically methyl or ethyl. Preferably the polymers will have 
at least 50%, and most preferably at least 60%, of the polymer chains with 
terminal vinylidene unsaturation. As indicated in WO-A-94/19426, 
ethylene/1-butene copolymers typically have vinyl groups terminating no 
more than about 10 percent of the chains, and internal mono-unsaturation 
in the balance of the chains. The nature of the unsaturation may be 
determined by FTIR spectroscopic analysis, titration or C-13 NMR. 
The oil-soluble polymeric hydrocarbon backbone may be a homopolymer (e.g., 
polypropylene) or a copolymer of two or more of such olefins (e.g., 
copolymers of ethylene and an alpha-olefin such as propylene or butylene, 
or copolymers of two different alpha-olefins). Other copolymers include 
those in which a minor molar amount of the copolymer monomers, e.g., 1 to 
10 mole %, is an .alpha.,.omega.-diene, such as a C.sub.3 to C.sub.22 
non-conjugated diolefin (e.g., a copolymer of isobutylene and butadiene, 
or a copolymer of ethylene, propylene and 1,4-hexadiene or 
5-ethylidene-2-norbornene). Atactic propylene oligomers typically having 
an Mn of from 700 to 5000 may also be used, as described in EP-A490454, as 
well as heteropolymers such as polyepoxides. 
One preferred class of olefin polymers is polybutenes and specifically 
poly-n-butenes, such as may be prepared by polymerization of a C.sub.4 
refinery stream. Other preferred classes of olefin polymers are EAO 
copolymers that preferably contain 1 to 50 mole % ethylene, and more 
preferably 5 to 48 mole % ethylene. Such polymers may contain more than 
one alpha-olefin and may contain one or more C.sub.3 to C.sub.22 
diolefins. Also useable are mixtures of EAO's of varying ethylene content. 
Different polymer types, e.g., EAO, may also be mixed or blended, as well 
as polymers differing in Mn; components derived from these also may be 
mixed or blended. 
The olefin polymers and copolymers used in the dispersant employed in the 
invention preferably have an Mn of from 700 to 5000, more preferably 1300 
to 4000. Polymer molecular weight, specifically Mn, can be determined by 
various known techniques. One convenient method is gel permeation 
chromatography (GPC), which additionally provides molecular weight 
distribution information (see W. W. Yau, J. J. Kirkland and D. D. Bly, 
"Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New 
York, 1979). Another useful method, particularly for lower molecular 
weight polymers, is vapor pressure osmometry (see, e.g., ASTM D3592). 
The degree of polymerisation D.sub.p of a polymer is: 
##EQU2## 
and thus for the copolymers of two monomers D.sub.p may be calculated as 
follows: 
##EQU3## 
Preferably, the degree of polymerisation for the polymer backbones used in 
the invention is at least 45, typically from 50 to 165, more preferably 55 
to 140. 
Particularly preferred copolymers are ethylene butene copolymers. 
Preferably, the olefin polymers and copolymers may be prepared by various 
catalytic polymerization processes using metallocene catalysts which are, 
for example, bulky ligand transition metal compounds of the formula: 
EQU [L].sub.m M[A].sub.n 
where L is a bulky ligand; A is a leaving group, M is a transition metal, 
and m and n are such that the total ligand valency corresponds to the 
transition metal valency. Preferably the catalyst is four co-ordinate such 
that the compound is ionizable to a 1.sup.+ valency state. 
The ligands L and A may be bridged to each other, and if two ligands A 
and/or L are present, they may be bridged. The metallocene compound may be 
a full sandwich compound having two or more ligands L which may be 
cyclopentadienyl ligands or cyclopentadienyl derived ligands, or they may 
be half sandwich compounds having one such ligand L. The ligand may be 
mono- or polynuclear or any other ligand capable of .eta.-5 bonding to the 
transition metal. 
One or more of the ligands may .pi.-bond to the transition metal atom, 
which may be a Group 4, 5 or 6 transition metal and/or a lanthanide or 
actinide transition metal, with zirconium, titanium and hafnium being 
particularly preferred. 
The ligands may be substituted or unsubstituted, and mono-, di-, tri, 
tetra- and penta-substitution of the cyclopentadienyl ring is possible. 
Optionally the substituent(s) may act as one or more bridges between the 
ligands and/or leaving groups and/or transition metal. Such bridges 
typically comprise one or more of a carbon, germanium, silicon, phosphorus 
or nitrogen atom-containing radical, and preferably the bridge places a 
one-atom link between the entities being bridged, although that atom may 
and often does carry other substituents. 
The metallocene may also contain a further displaceable ligand, preferably 
displaced by a cocatalyst--a leaving group--that is usually selected from 
a wide variety of hydrocarbyl groups and halogens. 
Such polymerizations, catalysts, and cocatalysts or activators are 
described, for example, in U.S. Pat. Nos. 4,530,914, 4,665,208, 4,808,561, 
4,871,705, 4,897,455, 4,937,299, 4,952,716, 5,017,714, 5,055,438, 
5,057,475, 5,064,802, 5,096,867, 5,120,867, 5,124,418, 5,153,157, 
5,198,401, 5,227,440, 5,241,025; EP-A-129368, 277003, 277004, 420436, 
520732; and WO-A-91/04257, 92/00333, 93/08199, 93/08221, 94/07928 and 
94/13715. 
The oil-soluble polymeric hydrocarbon backbone may be functionalized to 
incorporate a functional group into the backbone of the polymer, or as one 
or more groups pendant from the polymer backbone. The functional group 
typically will be polar and contain one or more hetero atoms such as P, O, 
S, N, halogen, or boron. It can be attached to a saturated hydrocarbon 
part of the oil-soluble polymeric hydrocarbon backbone via substitution 
reactions or to an olefinic portion via addition or cycloaddition 
reactions. Alternatively, the functional group can be incorporated into 
the polymer in conjunction with oxidation or cleavage of the polymer chain 
end (e.g., as in ozonolysis). 
Useful functionalization reactions include: halogenation of the polymer at 
an olefinic bond and subsequent reaction of the halogenated polymer with 
an ethylenically unsaturated functional compound (e.g., maleation where 
the polymer is reacted with maleic acid or anhydride); reaction of the 
polymer with an unsaturated functional compound by the "ene" reaction 
absent halogenation; reaction of the polymer with at least one phenol 
group (this permits derivatization in a Mannich base-type condensation); 
reaction of the polymer at a point of unsaturation with carbon monoxide 
using a Koch-type reaction to introduce a carbonyl group in an iso or neo 
position; reaction of the polymer with the functionalizing compound by 
free radical addition using a free radical catalyst; reaction with a 
thiocarboxylic acid derivative; and reaction of the polymer by air 
oxidation methods, epoxidation, chloroamination, or ozonolysis. 
The functionalized oil-soluble polymeric hydrocarbon backbone is then 
further derivatized with a nucleophilic reactant such as an amine, 
amino-alcohol, alcohol, metal compound or mixture thereof to form a 
corresponding derivative. Useful amine compounds for derivatizing 
functionalized polymers comprise at least one amine and can comprise one 
or more additional amine or other reactive or polar groups. These amines 
may be hydrocarbyl amines or may be predominantly hydrocarbyl amines in 
which the hydrocarbyl group includes other groups, e.g., hydroxy groups, 
alkoxy groups, amide groups, nitriles, imidazoline groups, and the like. 
Particularly useful amine compounds include mono- and polyamines, e.g. 
polyalkylene and polyoxyalkylene polyamines of about 2 to 60, conveniently 
2 to 40 (e.g., 3 to 20), total carbon atoms and about 1 to 12, 
conveniently 3 to 12, and preferably 3 to 9 nitrogen atoms in the 
molecule. Mixtures of amine compounds may advantageously be used such as 
those prepared by reaction of alkylene dihalide with ammonia. Preferred 
amines are aliphatic saturated amines, including, e.g., 1,2-diaminoethane; 
1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane; polyethylene 
amines such as diethylene triamine; triethylene tetramine; tetraethylene 
pentamine; and polypropyleneamines such as 1,2-propylene diamine; and 
di-(1,2-propylene)triamine. 
Other useful amine compounds include: alicyclic diamines such as 
1,4-di(aminomethyl) cyclohexane, and heterocyclic nitrogen compounds such 
as imidazolines. A particularly useful class of amines are the polyamido 
and related amido-amines as disclosed in U.S. Pat. Nos. 4,857,217; 
4,956,107; 4,963,275; and 5,229,022. Also useable is 
tris(hydroxymethyl)amino methane (THAM) as described in U.S. Pat. Nos. 
4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers, star-like 
amines, and comb-structure amines may also be used. Similarly, one may use 
the condensed amines disclosed in U.S. Pat. No. 5,053,152. The 
functionalized polymer is reacted with the amine compound according to 
conventional techniques as described in EP-A 208,560; U.S. Pat. Nos. 
4,234,435 and 5,229,022. 
The functionalized oil-soluble polymeric hydrocarbon backbones also may be 
derivatized with hydroxy compounds such as monohydric and polyhydric 
alcohols or with aromatic compounds such as phenols and naphthols. 
Polyhydric alcohols are preferred, e.g., alkylene glycols in which the 
alkylene radical contains from 2 to 8 carbon atoms. Other useful 
polyhydric alcohols include glycerol, mono-oleate of glycerol, 
monostearate of glycerol, monomethyl ether of glycerol, pentaerythritol, 
dipentaerythritol, and mixtures thereof. An ester dispersant may also be 
derived from unsaturated alcohols such as allyl alcohol, cinnamyl alcohol, 
propargyl alcohol, 1-cyclohexane-3-ol, and oleyl alcohol. Still other 
classes of the alcohols capable of yielding ashless dispersants comprise 
the ether-alcohols and including, for example, the oxy-alkylene, 
oxy-arylene. They are exemplified by ether-alcohols having up to 150 
oxy-alkylene radicals in which the alkylene radical contains from 1 to 8 
carbon atoms. The ester dispersants may be di-esters of succinic acids or 
acidic esters, i.e., partially esterified succinic acids, as well as 
partially esterified polyhydric alcohols or phenols, i.e., esters having 
free alcohols or phenolic hydroxyl radicals. An ester dispersant may be 
prepared by one of several known methods as illustrated, for example, in 
U.S. Pat. No. 3,381,022. 
A preferred group of ashless dispersants includes those substituted with 
succinic anhydride groups and reacted with polyalkylene amines, such as 
polyethylene amines (e.g., tetraethylene pentamine), aminoalcohols such as 
trismethylolaminomethane and optionally additional reactants such as 
alcohols and reactive metals e.g., pentaerythritol, and combinations 
thereof). Also useful are dispersants wherein a polyamine is attached 
directly to the backbone by the methods shown in U.S. Pat. Nos. 3,275,554 
and 3,565,804 where a halogen group on a halogenated hydrocarbon is 
displaced with various alkylene polyamines. 
Another class of ashless dispersants comprises Mannich base condensation 
products. Generally, these are prepared by condensing about one mote of an 
alkyl-substituted mono- or polyhydroxy benzene with about 1 to 2.5 moles 
of carbonyl compounds (e.g., formaldehyde and paraformaldehyde) and about 
0.5 to 2 moles polyalkylene polyamine as disclosed, for example, in U.S. 
Pat. No. 3,442,808. Such Mannich condensation products may include a 
polymer product of a metallocene cataylsed polymerisation as a substituent 
on the benzene group or may be reacted with a compound containing such a 
polymer substituted on a succinic anhydride, in a manner similar to that 
shown in U.S. Pat. No. 3,442,808. 
Examples of functionalized and/or derivatized olefin polymers based on 
polymers synthesized using metallocene catalyst systems are described in 
publications identified above. 
The dispersant can be further post-treated by a variety of conventional 
post treatments such as boration, as generally taught in U.S. Pat. Nos. 
3,087,936 and 3,254,025. This is readily accomplished by treating an acyl 
nitrogen-containing dispersant with a boron compound selected from the 
group consisting of boron oxide, boron halides, boron acids and esters of 
boron acids, in an amount to provide from about 0.1 atomic proportion of 
boron for each mole of the acylated nitrogen composition to about 20 
atomic proportions of boron for each atomic proportion of nitrogen of the 
acylated nitrogen composition. Usefully the dispersants contain from about 
0.05 to 2.0 wt. %, e.g. 0.05 to 0.7 wt. % boron based on the total weight 
of the borated acyl nitrogen compound. The boron, which appears be in the 
product as dehydrated boric acid polymers (primarily (HBO.sub.2).sub.3), 
is believed to attach to the dispersant imides and diimides as amine salts 
e.g., the metaborate salt of the diimide. Boration is readily carried out 
by adding from about 0.05 to 4, e.g., 1 to 3 wt. % (based on the weight of 
acyl nitrogen compound) of a boron compound, preferably boric acid, 
usually as a slurry, to the acyl nitrogen compound and heating with 
stirring at from 135.degree. to 190.degree. C., e.g., 
140.degree.-170.degree. C., for from 1 to 5 hours followed by nitrogen 
stripping. Alternatively, the boron treatment can be carried out by adding 
boric acid to a hot reaction mixture of the dicarboxylic acid material and 
amine while removing water. 
Also, B may be provided separately, for example as a B ester or as a B 
succinimide, made for example from a polyisobutylene succinic anhydride, 
where the polymer has a molecular weight of from 450 to 700. 
Particularly useful compositions of the invention are those containing 
ashless dispersants based on poly(isobutylene) polymers having a number 
average molecular weight of from 900 to 2500, substituted with succinic 
anhydride groups which have been further functionalised. Preferably, the 
dispersant contains at least 1.0, and desirably at least 1.3 succinic 
groups per polymer group. A preferred functionalising class of compounds 
contains at least one NH&lt; group. Generally, functionalisation is effected 
using from 0.5 equivalents to 2 moles of amine compound per equivalent of 
succinic anhydride substituted polymer. 
Other preferred ashless dispersants are the functionalised and derivatised 
olefin polymers based on ethylene alpha-olefin polymers previously 
described, produced using metallocene catalyst systems. These, preferably, 
have number average molecular weights of from 1600 to 3500. 
OIL-SOLUBLE METAL DETERGENTS 
Metal-containing or ash-forming detergents function both as detergents to 
reduce or remove deposits and as acid neutraliziers or rust inhibitors, 
thereby reducing wear and corrosion and extending engine life. Detergents 
generally comprise a polar head with a long hydrophobic tail, with the 
polar head comprising a metal salt of an acidic organic compound. The 
salts may contain a substantially stoichiometric amount of the metal in 
which case they are usually described as normal or neutral salts, and 
would typically have a total base number or TBN (as may be measured by 
ASTM D2896) of from 0 to 80. It is possible to include large amounts of a 
metal base by reacting an excess of a metal compound such as an oxide or 
hydroxide with an acidic gas such as carbon dioxide. The resulting 
overbased detergent comprises neutralised detergent as the outler layer of 
a metal base (e.g. carbonate) micelle. Such overbased detergents may have 
a TBN of 150 or greater, and typically of from 250 to 450 or more. 
Detergents that may be used include oil-soluble neutral and overbased 
sulfonates, phenates, sulfurized phenates, thiophosphonates, salicylates, 
and naphthenates and other oil-soluble carboxylates of a metal, 
particularly the alkali or alkaline earth metals, e.g., sodium, potassium, 
lithium, calcium, and magnesium. The most commonly used metals are calcium 
and magnesium, which may both be present in detergents used in a 
lubricant, and mixtures of calcium and/or magnesium with sodium. 
Particularly convenient metal detergents are neutral and overbased calcium 
and magnesium sulfonates having TBN of from 20 to 450 TBN, and neutral and 
overbased calcium phenates and sulfurized phenates having TBN of from 50 
to 450. 
Sulfonates may be prepared from sulfonic acids which are typically obtained 
by the sulfonation of alkyl substituted aromatic hydrocarbons such as 
those obtained from the fractionation of petroleum or by the alkylation of 
aromatic hydrocarbons. Examples included those obtained by alkylating 
benzene, toluene, xylene, naphthalene, diphenyl or their halogen 
derivatives such as chlorobenzene, chlorotoluene and chloronaqphthalene. 
The alkylation may be carried out in the presence of a catalyst with 
alkylating agents having from about 3 to more than 70 carbon atoms. The 
alkaryl sulfonates usually contain from about 9 to about 80 or more carbon 
atoms, preferably from about 16 to about 60 carbon atoms per alkyl 
substituted aromatic moiety. 
The oil soluble sulfonates or alkaryl sulfonic acids may be neutralized 
with oxides, hydroxides, alkoxides, carbonates, carboxylate, sulfides, 
hydrosulfides, nitrates, borates and ethers of the metal. The amount of 
metal compound is chosen having regard to the desired TBN of the final 
product but typically ranges from about 100 to 220 wt % (preferably at 
least 125 wt %) of that stoichiometrically required. 
Metal salts of phenols and sulfurised phenols are prepared by reaction with 
an appropriate metal compound such as an oxide or hydroxide and neutral or 
overbased products may be obtained by methods well known in the art. 
Sulfurised phenols may be prepared by reacting a phenol with sulfur or a 
sulfur containing compound such as hydrogen sulfide, sulfur monohalide or 
sulfur dihalide, to form products which are generally mixtures of 
compounds in which 2 or more phenols are bridged by sulfur containing 
bridges. 
ANTIWEAR AND ANTIOXIDANT AGENTS 
Dihydrocarbyl dithiophosphate metal salts are frequently used as antiwear 
and antioxidant agents. The metal may be an alkali or alkaline earth 
metal, or aluminium, lead, tin, molybdenum, manganese, nickel or copper. 
The zinc salts are most commonly used in lubricating oil in amounts of 0.1 
to 10, preferably 0.2 to 2 wt %, based upon the total weight of the 
lubricating oil composition. They may be prepared in accordance with known 
techniques by first forming a dihydrocarbyl dithiophosphoric acid (DDPA), 
usually by reaction of one or more alcohol or a phenol with P.sub.2 
S.sub.5 and then neutralising the formed DDPA with a zinc compound. For 
example, a dithiophosphoric acid may be made by reacting mixtures of 
primary and secondary alcohols. Alternatively, multiple dithiophosphoric 
acids can be prepared where the hydrocarbyl groups on one are entirely 
secondary in character and the hydrocarbyl groups on the others are 
entirely primary in character. To make the zinc salt, any basic or neutral 
zinc compound could be used but the oxides, hydroxides and carbonates are 
most generally employed. Commercial additives frequently contain an excess 
of zinc due to use of an excess of the basic zinc compound in the 
neutralisation reaction. 
The preferred zinc dihydrocarbyl dithiophosphates are oil soluble salts of 
dihydrocarbyl dithiophosphoric acids and may be represented by the 
following formula: 
##STR3## 
wherein R and R' may be the same or different hydrocarbyl radicals 
containing from 1 to 18, preferably 2 to 12, carbon atoms and including 
radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl and 
cycloaliphatic radicals. Particularly preferred as R and R' groups are 
alkyl groups of 2 to 8 carbon atoms. Thus, the radicals may, for example, 
be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl, 
i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, 
butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, butenyl. In order to 
obtain oil solubility, the total number of carbon atoms (i.e. R and R') in 
the dithiophosphoric acid will generally be about 5 or greater. The zinc 
dihydrocarbyl dithiophosphate can therefore comprise zinc dialkyl 
dithiophosphates. 
Oxidation inhibitors or antioxidants reduce the tendency of mineral oils to 
deteriorate in service. Oxidative deterioration can be evidenced by sludge 
in the lubricant, varnish-like deposits on the metal surfaces, and by 
viscosity growth. Such oxidation inhibitors include hindered phenols, 
alkaline earth metal salts of alkylphenolthioesters having preferably 
C.sub.5 to C.sub.12 alkyl side chains, calcium nonylphenol sulphide, oil 
soluble phenates and sulfurized phenates, phosphosulfurized or sulfurized 
hydrocarbons, phosphorous esters, metal thiocarbamates, oil soluble copper 
compounds as described in U.S. Pat. No. 4,867,890, and 
molybdenum-containing compounds. 
Aromatic amines having at least two aromatic groups attached directly to 
the nitrogen constitute another class of compounds that is frequently used 
for antioxidancy. While these materials may be used in small amounts, 
preferred embodiments of the present invention are free of these 
compounds. They are preferably used in only small amounts, i.e., up to 0.4 
wt %, or more preferably avoided altogether other than such amount as may 
result as an impurity from another component of the composition. 
Typical oil soluble aromatic amines having at least two aromatic groups 
attached directly to one amine nitrogen contain from 6 to 16 carbon atoms. 
The amines may contain more than two aromatic groups. Compounds having a 
total of at least three aromatic groups in which two aromatic groups are 
linked by a covalent bond or by an atom or group (e.g., an oxygen or 
sulphur atom, or a --CO--, --SO.sub.2 -- or alkylene group) and two are 
directly attached to one amine nitrogen also considered aromatic amines 
having at least two aromatic groups attached directly to the nitrogen. The 
aromatic rings are typically substituted by one or more substituents 
selected from alkyl, cycloalkyl, alkoxy, aryloxy, acyl, acylamino, 
hydroxy, and nitro groups. The amount of any such oil soluble aromatic 
amines having at least two aromatic groups attached directly to one amine 
nitrogen should preferably not exceed 0.4 wt % active ingredient. 
OTHER COMPONENTS 
Examples are metal rust inhibitors, viscosity index improvers, corrosion 
inhibitors, other oxidation inhibitors, friction modifiers, other 
dispersants, anti-foaming agents, anti-wear agents, pour point 
depressants, and rust inhibitors. Some are discussed in further detail 
below. 
Representative examples of suitable viscosity modifiers are 
polyisobutylene, copolymers of ethylene and propylene, polymethacrylates, 
methacrylate copolymers, copolymers of an unsaturated dicarboxylic acid 
and a vinyl compound, interpolymers of styrene and acrylic esters, and 
partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, 
and isoprenelbutadiene, as well as the partially hydrogenated homopolymers 
of butadiene and isoprene. 
Friction modifiers and fuel economy agents which are compatible with the 
other ingredients of the final oil may also be included. Examples are 
esters formed by reacting carboxylic acids and anhydrides with alkanols 
such as glyceryl monoesters of higher fatty acids, for example, glyceryl 
mono-oleate; esters of long chain polycarboxylic acids with diols, for 
example, the butane diol ester of a dimerized unsaturated fatty acid; 
oxazoline compounds; and alkoxylated alkyl-substituted mono-amines, 
diamines and alkyl ether amines, for example, ethoxylated tallow amine and 
ethoxylated tallow ether amine. The amines may be used as such or in the 
form of an adduct or reaction product with a boron compound such as a 
boric oxide, boron halide, metaborate, boric acid or a mono-, di- or 
trialkyl borate. Other friction modifiers are known. Other conventional 
friction modifiers generally consist of a polar terminal group (e.g. 
carboxyl or hydroxyl) covalently bonded to an oleophillic hydrocarbon 
chain. Esters of carboxylic acids and anhydrides with alkanols are 
described in U.S. Pat. No. 4,702,850. Examples of other conventional 
friction modifiers are described by M. Belzer in the "Journal of 
Tribology" (1992), Vol. 114, pp. 675-682 and M. Belzer and S. Jahanmir in 
"Lubrication Science" (1988), Vol. 1, pp. 3-26. 
A viscosity index improver dispersant functions both as a viscosity index 
improver and as a 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 
C.sub.4 to C.sub.24 unsaturated ester of vinyl alcohol or a C.sub.3 to 
C.sub.10 unsaturated mono-carboxylic acid or a C.sub.4 to C.sub.10 
di-carboxylic acid with an unsaturated nitrogen-containing monomer having 
4 to 20 carbon atoms; a polymer of a C.sub.2 to C.sub.20 olefin with an 
unsaturated C.sub.3 to C.sub.10 mono-or di-carboxylic acid neutralised 
with an amine, hydroxyamine or an alcohol; or a polymer of ethylene with a 
C.sub.3 to C.sub.20 olefin further reacted either by grafting a C.sub.4 to 
C.sub.20 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. 
Examples of dispersants and viscosity index improver dispersants may be 
found in European Patent Specification No. 24146 B. 
Pour point depressants, otherwise known as lube oil flow improvers, lower 
the minimum temperature at which the fluid will flow or can be poured. 
Such additives are well known. Typical of those additives which improve 
the low temperature fluidity of the fluid are C.sub.8 to C.sub.18 dialkyl 
fumarate/vinyl acetate copolymers, and polymethacrylates. Foam control can 
be provided by an antifoamant of the polysiloxane type, for example, 
silicone oil or polydimethyl siloxane. 
The amines may be used as such or in the form of an adduct or reaction 
product with a boron compound such as a boric oxide, boron halide, 
metaborate, boric acid or a mono-, di- or trialkyl borate. Other friction 
modifiers are known. Other conventional friction modifiers generally 
consist of a polar terminal group (e.g. carboxyl or hydroxyl) covalently 
bonded to an oleophillic hydrocarbon chain. Esters of carboxylic acids and 
anhydrides with alkanols are described in U.S. Pat. No. 4,702,850. 
Examples of other conventional friction modifiers are described by M. 
Belzer in the "Journal of Tribology" (1992), Vol. 114, pp. 675-682 and M. 
Belzer and S. Jahanmir in "Lubrication Science" (1988), Vol. 1, pp. 3-26. 
Rust inhibitors selected from the group consisting of non-ionic 
polyoxyalkylene polyols and esters thereof, polyoxylalkylene phenols, and 
anionic alkyl sulfonic acids may be used. 
Copper and lead bearing corrosion inhibitors may be used. Typically such 
compounds are the thiadiazole polysulfides containing from 5 to 50 carbon 
atoms, their derivatives and polymers thereof. Derivatives of 1,3,4 
thiadiazoles such as those described in U.S. Pat. Nos. 2,719,125; 
2,719,126; and 3,087,932; are typical. Other similar materials are 
described in U.S. Pat. Nos. 3,821,236; 3,904,537; 4.097,387; 4,107,059; 
4,136,043; 4,188,299; and 4,193,882. Other additives are the thio and 
polythio sulfenamides of thiadiazoles such as those described in UK Patent 
Specification No. 1,560,830. Benzotriazoles derivatives also fall within 
this class of additives. 
A small amount of a demulsifying component may be used. A preferred 
demulsifying component is described in EP 330,522. It is obtained by 
reacting an alkylene oxide with an adduct obtained by reacting a 
bis-epoxide with a polyhydric alcohol. This demulsifier may be used at a 
level not exceeding 0.1 mass % active ingredient. A treat rate of 0.001 to 
0.05 mass % active ingredient is convenient. 
Some of the above-mentioned additives can provide a multiplicity of 
effects; thus for example, a single additive may act as a 
dispersant-oxidation inhibitor. This approach is well known and need not 
be further elaborated herein. 
Each additive is typically blended into the basestock oil in an amount 
which enables the additive to provide its desired function. 
Representative effect amounts of such additives, when used in crankcase 
lubricants, are listed below. All the values listed are stated as mass 
percent active ingredient. 
______________________________________ 
MASS % MASS % 
ADDITIVE (Broad) (Preferred) 
______________________________________ 
Ashless Dispersant 0.1-20 1-8 
Metal Detergents 0.1-15 0.2-9 
Corrosion Inhibitor 0-5 0-1.5 
Metal Dihydrocarbyl Dithiophosphate 0.1-6 0.1-4 
Antioxidant 0-5 0.01-2 
Pour Point Depressant 0.01-5 0.01-1.5 
Antifoaming Agent 0-5 0.001-0.15 
Supplemental Antiwear Agents 0-1.0 0-0.5 
Friction Modifier 0-5 0-1.5 
Viscosity Modifier 0.01-10 0.25-3 
Basestock Balance Balance 
______________________________________ 
All weight percents expressed herein (unless otherwise indicated) are based 
on active ingredient (A.I.) content of the additive, and/or upon the total 
weight of any additive-package, or formulation which will be the sum of 
the A.I. weight of each additive plus the weight of total oil or diluent. 
The components may be incorporated into a base oil in any convenient way. 
Thus, each of the components can be added directly to the oil by 
dispersing or dissolving it in the oil at the desired level of 
concentration. The individual components may be singly or in 
sub-combinations. Thus the detergent system is present when individual 
detergents are added so that collectively the features of the system are 
present. Such blending may occur at ambient temperature or at an elevated 
temperature. 
Preferably all the additives except for the viscosity modifier and the pour 
point depressant are blended into a concentrate or additive package 
described, that is subsequently blended into basestock to make finished 
lubricant. Use of such concentrates is conventional. The concentrate will 
typically be formulated to contain the additive(s) in proper amounts to 
provide the desired concentration in the final formulation when the 
concentrate is combined with a predetermined amount of base lubricant. 
It will be understood that the various components of the composition, the 
essential components as well as the optimal and customary components, may 
react under the conditions of formulation, storage, or use, and that the 
invention also provides the product obtainable or obtained as a result of 
any such reaction. 
While the dispersant and individual detergent components may be added to 
the concentrate singly, a particularly preferred concentrate is made by 
preblending the dispersant with the entire detergent system in accordance 
with the method described in U.S. Pat. No. 4,938,880. That patent 
describes making a premix of dispersant and metal detergents that is 
pre-blended at a temperature of at least about 100.degree. C. for a period 
of 1 to 10 hours. Thereafter the pre-mix is cooled to at least 85.degree. 
C. and the additional components are added. 
The final formulations may employ from 2 to 15 mass % and preferably 5 to 
15 mass %, typically about 10 mass % of the concentrate or additive 
package with the remainder being base oil. 
The invention is applicable to a variety of lubricant viscosity grades such 
as SAE 0W-X, SAE 5W-X, and SAE 10W-X, where X is 20, 30, 40 or 50.

EXAMPLES 
This invention will be further understood by reference to the following 
examples, wherein all parts are parts by weight, unless otherwise noted 
and which include preferred embodiments of the invention. 
TEST PROCEDURE 
The procedure used was the VW PV 1449, or T-4 test procedure, which is run 
in a 2.0 litre, 62 kW, four cylinder gasoline engine. The procedure is as 
follows. After a 10 hour "run in" and a 2 hour "flush run", the engine is 
run for 248 hours on test comprising 192 hours of a cyclic procedure and 
56 hours of constant speed running. No oil "top up" is permitted during 
the test. At the end of the test procedure, the used oil is assessed for 
viscosity, viscosity increase and total base number. The pistons from the 
engine are assessed for "ring stick" and piston cleanliness. 
The VW 502.00 specification of March 1997, Central Standard 57 221 
describes limits for VW acceptance of a lubricant. 
Experience has shown that viscosity increase is a critical parameter, the 
limit being approximately 130% with an adjustment derived from reference 
oil testing. 
FORMULATIONS TESTED 
A series of four SAE 10W40 multigrade crankcase lubricating oils meeting 
API SH/CD specifications was prepared from a basestock, a detergent 
inhibitor package (DI package) containing an ashless dispersant, ZDDP 
antioxidant, metal-containing detergents, friction modifier, demulsifier 
and an antifoam agent, and a separate viscosity modifier which is an oil 
solution of an ethylene-propylene copolymer having 25 SSI. The ashless 
dispersant was a conventional borated polyisobutenyl succinimide 
dispersant (PIBSA/PAM). 
The four test oils differed primarily in the content of polyalphaolefin 
(PAO) as follows: 
______________________________________ 
Oil A 1 2 3 
______________________________________ 
PAO Content (mass %) 
10 29.9 45 50 
______________________________________ 
The mineral oil content and viscosity modifier treat rate were also 
adjusted because of the changing PAO content. 
The four lubricants were tested in the above-described VW PV 1449 
procedure. 
TEST RESULTS 
At the end of the engine test the viscosity increases of these lubricant 
were found to be: 
______________________________________ 
Oil A 1 2 3 
______________________________________ 
Viscosity Increase (%) 
301 190 103 64.5 
______________________________________ 
The PAO used in the oils was a polyalphaolefin with a nominal viscosity at 
100.degree. C. of 6 cSt. Oil A is a comparison oil and oils 1, 2 and 3 are 
oils of the invention. 
It is therefore seen that the viscosity increase is significantly 
diminished by use of increasing proportions of PAO in the basestock, to 
the extent that test oils 2 and 3 easily meet the demanding viscosity 
increase requirements of the VW PV 1449 procedure.