Crankcase lubricant compositions and method of improving engine deposit performance

A low phosphorus passenger car motor oil containing an oil of lubricating viscosity as the major component and a tri-metal detergent mixture as a minor component, wherein the tri-metal detergent mixture comprises at least one calcium overbased metal detergent, at least one magnesium overbased metal detergent and at least one sodium overbased metal detergent, wherein the tri-metal detergent mixture is present in the oil composition in an amount such that the total TBN contributed to the oil composition by the tri-metal detergent mixture is from about 2 to about 12, and wherein the calcium overbased detergent contributes from about 8 to about 42% of the total TBN contributed by the tri-metal detergent mixture, the magnesium overbased detergent contributes from about 29 to about 60% of the total TBN contributed by the tri-metal detergent mixture, and the sodium overbased detergent contributes from about 15 to about 64% of the total TBN contributed by the tri-metal detergent mixture.

FIELD OF THE INVENTION 
The present invention relates to crankcase lubricants, preferably low 
phosphorus crankcase lubricants, which contain a tri-metal mixture of 
detergents and which are characterized by unexpectedly superior engine 
deposit performance. 
BACKGROUND OF THE INVENTION 
In mid-1994, the American Automobile Manufacturers Association (AAMA) and 
the Japan Automobile Manufacturers Association (JAMA) jointly issued new 
minimum performance specifications for gasoline engine oils through the 
International Lubricants Standardization and Approval Committee (ILSAC). 
Included among the new specifications for ILSAC GF-2 oils were a number of 
ASTM Sequence engine tests, similar to those needed to satisfy API service 
categories, certain physical and chemical property requirements, and 
several new bench tests, including the Thermo-Oxidation Engine Oil 
Simulation Test (TEOST; TEOST is a registered trademark of Tannas Co.). 
The TEOST was originally developed to evaluate the deposit formation 
tendencies of API SF quality engine oils brought in contact with very hot 
turbocharger components, and was included in GF-2 evaluation to probe the 
ability of a lubricant to control deposits in other high temperature areas 
of an engine. The TEOST, which is more fully described in SAE 932837, SAE 
962038 and SAE 962039, is a high temperature deposit bench test which is 
performed by circulating a candidate oil through an oxidation reactor and 
a deposition zone made up of a depositor rod axially aligned with an outer 
tube. The temperature of the reactor and of the depositor rod are 
independently controlled. 
The candidate oil to be evaluated (approximately 100 ml), along with iron 
naphthenate catalyst (100 ppm), is added to the oxidation reactor. The 
temperature of the mixture is raised and is maintained at 100.degree. C., 
while it is contacted with a gas stream consisting of air, nitrous oxide 
(N.sub.2 O) and water. Throughout the test, the candidate oil is slowly 
pumped (at a rate of about 0.4-0.5 ml/min) through the annulus between the 
depositor rod and the outside casing, while the rod is cycled through a 
preset temperature program which regularly raises the rod temperature to 
480.degree. C. With the exception of the initial ramp to 200.degree. C., 
the temperature of the rod is cycled from 200.degree. C. to 480.degree. C. 
approximately every 10 minutes. After running the test for 12 cycles 
(approximately two hours), the candidate oil is carefully collected and 
filtered through a pre-weighed filter to trap any insoluble material. The 
test equipment is then cleaned with a solvent and the used solvent is also 
collected and passed through the same filter previously used to filter the 
candidate oil. The filter is dried and weighed to determine the filter 
deposits. The depositor rod, which was weighed prior to initiation of the 
test, is dried and weighed to determine the weight of the deposits 
accumulated on the rod. The total deposits is the sum of the rod and 
filter deposits and is reported in milligrams (mg). The current ISLAC GF-2 
pass/fail limit for the TEOST is a total deposit weight of 60 mg. 
To meet the need for GF-2 crankcase lubricating oils, all of which must 
pass the TEOST and must perform adequately when used in a variety of 
engines under various operating conditions, a broad range of chemicals 
have been added to lubricating oil basestocks. Among such chemical 
additives are the overbased metal detergents, such as overbased alkali 
metal and overbased alkaline earth metal alkylaryl sulfonates, phenates, 
salicylates and other carboxylates, naphthenates, and the like. Overbased 
metal detergents function both as detergents and acid neutralizers, 
thereby reducing wear and corrosion and extending engine life. Overbased 
metal detergents are known to reduce the amount of engine deposits that 
are formed, as compared to comparable lubricating oils formulated without 
any metal detergents. Accordingly, it is typical to incorporate one or 
more metal detergents in a lubricating oil composition in amounts of from 
about 0.01 to about 10%, and preferably from about 0.1 to about 5%, by 
weight, based on the total weight of the oil composition, to achieve 
lubricating oil formulations which pass current GF-2 specifications. 
There are numerous patents which disclose crankcase lubricants that contain 
overbased metal detergents. For example, U.S. Pat. No. 5,256,322 to Cohu 
relates to a lubricating oil for use in methanol fueled internal 
combustion engines, wherein the lubricating oil has a total base number 
(TBN) of from about 9.0 to about 14.0 and comprises a base oil and a 
combination of an overbased sodium sulfonate and at least one overbased 
metal sulfonate selected from the group of overbased calcium sulfonates, 
overbased magnesium sulfonates, and mixtures thereof. The overbased sodium 
sulfonate is present in the lubricating oil in an amount sufficient to 
provide a base number of from about 1.0 to about 2.0, and the overbased 
calcium sulfonates and/or overbased magnesium sulfonates are present in an 
amount sufficient to provide a base number of from about 8.0 to about 
12.0. This patent teaches that the claimed combination of metal sulfonates 
is surprisingly effective in neutralizing carboxylic acids resulting from 
the combustion of methanol in internal combustion engines. This patent 
discloses the results of engine tests designed to determine the effects of 
alcohol fuels on engine wear. However, there is no disclosure as to the 
effects, if any, on engine deposit performance. 
U.S. Pat. No. 5,232,614 to Colclough, et al. discloses lubricating oils 
incorporating substituted para-phenylene diamines as anti-oxidants to 
combat thickening and sludge formation after prolonged exposure to oxygen 
at elevated temperatures. In addition to the para-phenylene diamine 
anti-oxidant, the lubricating oils may contain a number of conventional 
additives, including overbased metal detergents. At column 11, lines 8-11 
of this patent, a preference toward adding a combination of metal 
detergents to the lubricating oils is disclosed. However, no specific 
advantages of adding a combination of overbased metal detergents is 
disclosed; nor is there any discussion of engine deposit performance 
tests, nor of adding any particular combination of metal detergents in 
critical amounts. 
EP Application 0 317 348 A1 (Exxon Chemical Patents, Inc.) discloses 
crankcase lubricating oil compositions for low temperature internal 
combustion engines. The compositions incorporate a mixture of at least one 
calcium overbased sulfonate or phenate and at least one magnesium 
overbased sulfonate or phenate. At page 6, lines 26-29 of this application 
it is disclosed that other alkaline earth and/or alkali metal detergents 
can be incorporated in the lubricating oil compositions. There are no 
engine deposit test results discussed in this application; nor is there 
any suggestion that a synergistic reduction of engine deposits might be 
achieved by using a particular tri-metal detergent combination. The main 
thrust of this application is the discovery of a surprisingly pronounced 
relationship between decreased cylinder and ring wear and the proportions 
of mixed calcium/magnesium detergent inhibitors and mixed 
primary/secondary zinc antiwear agent in crankcase oil compositions. 
Despite all of the advances that have been made in the lubricating oil 
formulating art, a need remains for lubricating oils that exceed the 
current TEOST and other engine deposit performance requirements, without 
otherwise compromising oil performance. 
SUMMARY OF THE INVENTION 
Surprisingly, a lubricating oil composition capable of achieving 
significantly improved engine deposit performance can be formulated by 
incorporating into a passenger car motor oil (PCMO), preferably a low 
phosphorus PCMO (e.g., containing less than about 0.1 wt.% phosphorus), in 
amounts hereinafter set forth, a tri-metal detergent mixture of at least 
one overbased calcium-containing detergent, at least one overbased 
magnesium-containing detergent and at least one overbased 
sodium-containing detergent. It has been found that the present tri-metal 
detergent mixture results in unexpectedly superior engine deposit 
performance when compared to the results obtained when identical calcium-, 
magnesium- and sodium-containing detergents are incorporated in the 
lubricating oil composition either individually or in binary mixtures. The 
engine deposit performance of the present lubricating oil composition can 
be further improved by adding one or more neutral soaps to the 
composition. 
The calcium-, magnesium-, and sodium-containing overbased detergents may 
comprise the respective metal salt of any oil soluble acid having a total 
base number (TBN) in excess of about 100 (mg KOH, as measured by ASTM 
D2896), typically in excess of about 200, and preferably in excess of 
about 300, e.g., 400. In one aspect of the invention, each of the 
calcium-, magnesium-, and sodium-containing overbased detergents comprises 
a metal sulfonate having a TBN in excess of 100. In another aspect, each 
of the calcium-, magnesium-, and sodium-containing overbased detergents 
comprises a metal phenate having a TBN in excess of 100. In yet another 
aspect, each of the calcium-, magnesium-, and sodium-containing overbased 
detergents comprises a metal carboxylate having a TBN in excess of 100. In 
still another aspect, at least one of the calcium-, magnesium- and/or 
sodium-containing overbased detergents comprises a metal sulfonate having 
a TBN in excess of 100, and at least one other of the calcium- magnesium- 
and/or sodium-containing overbased detergents comprises a metal phenate 
and/or carboxylate having a TBN is excess of 100. Typically, the neutral 
soaps which are added to the lubricating oil composition of this invention 
are metal sulfonates, phenates and/or carboxylates, e.g., calcium or 
sodium sulfonates, phenates or carboxylates, having a TBN of less than 
about 100, e.g., less than about 50, and preferably less than about 25. 
The calcium-, magnesium- and sodium-containing overbased tri-metal 
detergent mixture is added to the lubricating oil composition such that 
the total TBN contributed to the fully formulated oil is from about 2 to 
about 10 mg KOH. Typically, the tri-metal overbased detergent mixture 
comprises from about 0.1 to about 10 wt.% of the fully formulated oil, and 
the relative amounts of the calcium, magnesium and sodium overbased 
detergents are such that the calcium overbased detergent contributes from 
about 8 to about 42% of the total TBN of the fully formulated oil, while 
the magnesium overbased detergent and the sodium overbased detergent 
contributes from about 29 to about 60% and from about 15 to about 64% of 
the total TBN, respectively.

DETAILED DESCRIPTION 
The lubricating oil composition of the present invention comprises a base 
oil of lubricating viscosity as the major component. The base oil may be 
selected from any of the synthetic or natural oils typically used as 
crankcase lubricating oils for spark-ignited and compression-ignited 
engines. The base oil conveniently has a viscosity of about 2.5 to about 
12 cSt or mm.sup.2 /s and preferably about 2.5 to about 9 cSt or mm.sup.2 
/s at 100.degree. C. Mixtures of synthetic and natural base oils may be 
used if desired. Particularly useful base oils result in single grade and 
multigrade oils of 0W to 50W, including permutations and combinations 
thereof, e.g., 0W, 5W, 10W, 20W, etc., 0W20, 5W20, 10W30, 20W50, etc. 
In addition to the base oil of lubricating viscosity, the present 
lubricating oil composition contains, as an essential component, a minor 
amount of a tri-metal mixture comprised of at least one calcium overbased 
detergent, at least one magnesium overbased detergent, and at least one 
sodium overbased detergent. 
Typically, the calcium, magnesium and sodium overbased detergents are salts 
of an oil soluble acid having a total base number (TBN) in excess of 100, 
typically in excess of 200, and preferably in excess of 300, e.g., about 
400. 
Conveniently, the calcium, magnesium and sodium overbased detergents are 
salts of an oil soluble sulfonic acid which are produced by heating a 
mixture of an oil-soluble sulfonate or alkaryl sulfonic acid with an 
amount of a calcium, magnesium and/or sodium compound in excess of the 
amount required to completely neutralize any sulfonic acid present, and 
thereafter forming a dispersed carbonate complex by reacting the excess 
metal with carbon dioxide. The sulfonic acids typically are 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 include those obtained by alkylating 
benzene, toluene, xylene, naphthalene, diphenyl or their halogen 
derivatives such as chlorobenzene, chlorotoluene and chloronaphthalene. 
The alkylation may be carried out in the presence of a catalyst with 
alkylating agents having from 3 to more than 30 carbon atoms. For example, 
haloparaffins, olefins obtained by dehydrogenation of paraffins, or 
polyolefins produced from ethylene or propylene are all suitable. The 
alkaryl sulfonates usually contain from about 9 to about 70 or more carbon 
atoms, preferably from about 16 to about 50 carbon atoms per alkyl 
substituted aromatic moiety. 
The oil soluble sulfonates may be neutralized with calcium, magnesium 
and/or sodium compounds, e.g., oxides, hydroxides, alkoxides, carbonates, 
carboxylate, sulfides, hydrosulfides, nitrates, borates and ethers. The 
amount of calcium, magnesium and/or sodium compound that is used to 
neutralize the oil soluble sulfonate is chosen having regard to the 
desired TBN of the final product, but the amount typically ranges from 
about 100 to about 220 wt. %, preferably at least 125 wt. % of the oil 
soluble sulfonate being neutralized. 
Various other preparations of alkali metal and alkaline earth metal 
overbased alkaryl sulfonates are disclosed, for example, in U.S. Pat. Nos. 
3,150,088 and 3,150,089, wherein overbasing is accomplished by hydrolysis 
of an alkoxide-carbonate complex with the alkaryl sulfonate in a 
hydrocarbon solvent-diluent oil. 
Preferred calcium, magnesium and sodium sulfonate detergents are alkyl 
aromatic sulfonates having a high TBN, as measured by ASTM D2896, ranging 
from about 300 to about 440. Typical overbased calcium alkyl aromatic 
sulfonates have a calcium sulfonate content ranging from about 30 to about 
90 wt. % (A.I.). Typical overbased magnesium alkyl aromatic sulfonates 
have a magnesium sulfonate content ranging from about 5 to about 70 wt. % 
(A.I.). Typical overbased sodium alkyl aromatic sulfonates have a sodium 
sulfonate content ranging from about 5 to about 80 wt. % (A.I.). Typical 
values of metals concentration in overbased detergents are from about 5 to 
20 wt. % in a diluted additive. Thus, at an active ingredient 
concentration of 55 wt. %, the concentration of metal in a detergent 
(undiluted) is from about 9 to about 37 wt. %. 
Other overbased calcium, magnesium and/or sodium detergents which may be 
used in place of or in combination with the above-described salts of 
sulfonic acids include, for example, overbased phenates, sulfurized 
phenates, thiophosphonates, salicylates, methylene bridged 
salicylate-phenates and naphthenates and other oil-soluble carboxylates; 
provided, however, that there always is used a mixture of calcium 
overbased detergent, magnesium overbased detergent and sodium overbased 
detergent in the amounts disclosed herein. 
Typically, the tri-metal overbased detergent mixture, i.e., the mixture of 
calcium overbased detergent, magnesium overbased detergent and sodium 
overbased detergent, is present in the lubricating oil composition in an 
amount such that the total TBN contributed to the fully formulated oil 
composition by the tri-metal overbased detergent mixture is from about 2 
to about 12 mg KOH, e.g., from about 3 to about 9, and preferably from 
about 3.5 to about 8. Thus, when using overbased detergents having a TBN 
in excess of about 100, the amount of tri-metal overbased detergent 
mixture present in the lubricating oil composition typically is from about 
0.1 to about 10 wt. % (A.I.), e.g., from about 0.3 to about 6 wt. % 
(A.I.), and preferably from about 0.1 to about 3 wt. % (A.I.), based on 
the total weight of the fully formulated lubricating oil composition. In 
still more preferred aspects, the mixture of calcium overbased detergent, 
magnesium overbased detergent and sodium overbased detergent is present in 
the lubricating oil composition in an amount of from about 0.6 to about 
0.8 wt. %, e.g., about 0.65 wt. %. 
The relative amounts of the calcium overbased detergent(s), magnesium 
overbased detergent(s) and sodium overbased detergent(s), and thus the 
percentage of the total TBN of the fully formulated lubricating oil 
composition contributed by the respective detergents, may vary depending 
in part on the particular detergents employed. However, the amounts of the 
various detergents are selected such that the calcium overbased 
detergent(s) typically contributes from about 8 to about 42%, and 
preferably from about 17 to about 42% of the total TBN contributed by the 
tri-metal detergent mixture. Most preferably, the calcium overbased 
detergent(s) contributes from about 22 to about 37% of the total TBN 
contributed by the tri-metal detergent mixture. 
The magnesium overbased detergent(s) typically contributes from about 29 to 
about 60%, and preferably from about 29 to about 50% of the total TBN 
contributed by the tri-metal detergent mixture. Most preferably, the 
magnesium overbased detergent(s) contributes from about 29 to about 40% of 
the total TBN contributed by the tri-metal detergent mixture. Similarly, 
the sodium overbased detergent(s) typically contributes from about 15 to 
about 64%, and preferably from about 22 to about 43% of the total TBN 
contributed by the tri-metal detergent mixture. Most preferably, the 
sodium overbased detergent(s) contributes from about 30 to about 43% of 
the total TBN contributed by the tri-metal detergent mixture. 
The relative amounts of the calcium overbased detergent(s), the magnesium 
overbased detergent(s) and sodium overbased detergent(s) will be more 
fully understood with reference to FIG. 1, wherein the percentage of the 
total TBN of a fully formulated oil composition contributed by a 400 TBN 
sodium alkylbenzene sulfonate is shown along the left-hand axis of the 
triangular graph, wherein the percentage of the total TBN contributed by a 
400 TBN calcium alkylbenzene sulfonate is shown along the right-hand axis 
of the triangular graph, wherein the percentage of the total TBN 
contributed by a 400 TBN magnesium alkylbenzene sulfonate is shown along 
the bottom axis of the triangular graph, wherein typical contributions to 
the total TBN by the various detergents that are added to the present 
lubricating oil compositions fall within the largest of the shaded areas 
of the graph, wherein relatively preferred contributions to the total TBN 
by the various detergents fall within the second largest of the shaded 
areas of the graph, and wherein still more preferred contributions to the 
total TBN by the various detergents fall within the smallest of the shaded 
areas of the graph. 
In preferred compositions, one or more neutral soaps, such as a neutral 
alkali metal or alkaline earth metal sulfonate, phenate, sulfurized 
phenate, thiophosphonate, salicylate and naphthenate or other oil-soluble 
carboxylate, is added to the lubricating oil composition to further 
improve engine deposit performance. Neutral soaps typically have a TBN 
less than about 100, preferably less than about 50, e.g., less than about 
25, and contribute very little to the total TBN of the finished oil. Such 
neutral soaps are described, for example, in U.S. Pat. No. 5,232,614. 
Typically, when the neutral soaps are added to the fully formulated 
lubricating oil composition, they are added in an amount of from about 
0.05 to about 5 wt. % (A.I.), e.g., from about 0.1 to about 3 wt. %, and 
preferably from about 0.2 to about 2 wt. %, based on the total weight of 
the fully formulated lubricating oil composition. 
It has been observed that when a neutral soap is added to a candidate oil 
which already contains a tri-metal overbased detergent mixture, the engine 
deposit performance of the candidate oil improves in an additive sense; 
whereas when a tri-metal overbased detergent mixture is added to an 
otherwise conventional candidate oil, regardless of whether there is a 
further addition of a neutral soap, a synergistic improvement in the 
engine deposit performance of the candidate oil is observed. 
In addition to the base lubricating oil and the tri-metal mixture of 
overbased detergents, which are essential components, and the neutral 
soap, which is a preferred component, the lubricating oil composition of 
this invention typically contains one or more or optional components, such 
as ashless nitrogen containing dispersants, ashless nitrogen containing 
dispersant viscosity modifiers, antiwear and antioxidant agents, 
supplemental dispersants, stabilizers, such as polyisobutenyl succinic 
acids and/or anhydrides having a mean average molecular weight of from 
about 400 to about 2500, friction modifiers, rust inhibitors, anti-foaming 
agents, demulsifiers, and pour point depressants, and the like. 
In general, suitable ashless nitrogen containing dispersants comprises an 
oil solubilizing polymeric hydrocarbon backbone derivatized with nitrogen 
substituents that are capable of associating with polar particles to be 
dispersed. Typically, the dispersants comprise a nitrogen containing 
moiety attached to the polymer backbone, often via a bridging group, and 
may be selected from any of the well known oil soluble salts, amides, 
imides, amino-esters, 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. 
The oil soluble polymeric hydrocarbon backbone is typically an olefin 
polymer, especially polymers comprising a major molar amount (i.e. greater 
than 50 mole %) of a C.sub.2 to C.sub.18 olefin (e.g., ethylene, 
propylene, butylene, isobutylene, pentene, octene-1, styrene), and 
typically a C.sub.2 to C.sub.5 olefin. The oil soluble polymeric 
hydrocarbon backbone may be a homopolymer (e.g. polypropylene or 
polyisobutylene) or a copolymer of two or more of such olefins (e.g. 
copolymers of ethylene and an alpha-olefin such as propylene and 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 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). 
Preferred olefin polymers include polybutenes and specifically 
polyisobutenes (PIB) or poly-n-butenes, such as may be prepared by 
polymerization of a C.sub.4 refinery stream. 
Suitable olefin polymers and copolymers may be prepared by cationic 
polymerization of hydrocarbon feedstreams, usually C.sub.3 -C.sub.5, in 
the presence of a strong Lewis acid catalyst and a reaction promoter, 
usually an organoaluminum such as HCl or ethylaluminum dichloride. Tubular 
or stirred reactors may be used. Such polymerizations and catalysts are 
described, e.g., in U.S. Pat. No. 4,935,576. Fixed bed catalyst systems 
also may be used as disclosed, e.g., in U.S. Pat. No. 4,982,045. Most 
commonly, polyisobutylene polymers are derived from Raffinate I refinery 
feedstreams. Conventional Ziegler-Natta polymerization also may be 
employed to provide olefin polymers suitable for preparing dispersants and 
other additives. 
The oil soluble polymeric hydrocarbon backbone usually will have a number 
average molecular weight (Mn) within the range of from about 300 to about 
10,000. The Mn of the backbone is preferably within the range of 500 to 
10,000, more preferably 700 to 5,000 where the use of the backbone is to 
prepare a component having the primary function of dispersancy. Olefin 
polymers which are particularly useful for preparing dispersants have a Mn 
within the range of from 1500 to 3000. Where the component is also 
intended to have a viscosity modification effect it is desirable to use 
higher molecular weight polymers, typically polymers having a Mn of from 
about 2,000 to about 20,000; and if the component is intended to function 
primarily as a viscosity modifier, polymers having a Mn of from 20,000 to 
500,00 or greater should be used. The functionalized olefin polymers used 
to prepare dispersants preferably have approximately one terminal double 
bond per polymer chain. 
The Mn for such polymers can be determined by several known techniques. A 
convenient method for such determination is by 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. 
The oil soluble polymeric hydrocarbon backbone may be functionalized to 
incorporate a functional group into the backbone of the polymer, or as 
pendant groups 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. The functional group can be attached to a saturated 
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 by oxidation or cleavage of a 
small portion of the end of the polymer (e.g., as in ozonolysis). 
Useful functionalization reactions include, for example, halogenation of 
the polymer at an olefinic bond and subsequent reaction of the halogenated 
polymer with an ethylenically unsaturated functional compound; reaction of 
the polymer with an unsaturated functional compound by the "ene" reaction 
absent halogenation (e.g., maleation where the polymer is reacted with 
maleic acid or anhydride); 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 amine, amino-alcohol, or mixture 
thereof to form oil soluble salts, amides, imides, amino-esters, an 
oxazolines. Useful amine compounds include mono- and (preferably) 
polyamines, most preferably polyalkylene polyamines, of abut 2 to 60, 
preferably 2 to 40 (e.g. 3 to 20), total carbon atoms and about 1 to 12, 
preferably 3 to 12, and most preferably 3 to 9 nitrogen atoms in the 
molecule. These amines may be hydrocarbyl amines or may be predominantly 
hydrocarbyl amines in which the hydrocarbyl group includes other groups, 
and the like. Preferred amines are aliphatic saturated amines. 
Non-limiting examples of suitable amine compounds include: 
1,2-diaminoethane; polyethylene amines such as diethylene triamine and 
tetraethylene pentamine; and polypropyleneamines such as 1,2-propylene 
diamine. 
Other useful amine compounds include, for example, alicyclic diamines such 
as 1,4-di(aminomethyl) cyclohexane; heterocyclic nitrogen compounds such 
as imidazolines; polyoxyalkylene polyamines; polyamido and related 
amido-amines; and tris(hydroxymethyl)amino methane (THAM). Dendrimers, 
star-like amines, and comb-structure amines also may be used, as may 
mixtures of amine compounds such as those prepared by reaction of alkylene 
dihalides with ammonia. 
A preferred group of nitrogen containing ashless dispersants includes those 
derived from polyisobutylene substituted with succinic anhydride groups 
and reacted with polyethylene amines (e.g., tetraethylene pentamine) or 
with aminoalcohols and, optionally, with additional reactants such as 
alcohols. 
The nitrogen containing 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 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 atomic proportion of nitrogen of the acylated nitrogen 
composition to about 20 atomic proportions of boron for each atomic 
proportion of nitrogen of the acylated nitrogen composition. 
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, which is usually added as a slurry to the acyl 
nitrogen compound and heating with stirring at from about 135.degree. C. 
to about 190.degree. C., e.g., 140.degree. to 170.degree. C. for from 1 to 
5 hours followed by nitrogen stripping. 
Suitable viscosity modifiers (or viscosity index improvers) that may be 
added to the present lubricating oil composition include oil soluble 
polymers having a weight average molecular weight of from about 10,000 to 
1,000,000, preferably 20,000 to 500,000, as determined by gel permeation 
chromatography or light scattering methods. 
Representative examples of such polymers include polyisobutylene, 
copolymers of ethylene and propylene and higher alpha-olefins, 
polymethacrylates, methacrylate copolymers, polyalkylmethacrylates, 
copolymers of styrene and acrylic esters, copolymers of a vinyl compound 
and an unsaturated dicarboxylic acid, and partially hydrogenated 
copolymers of styrene/isoprene, styrene/butadiene, and isoprene/butadiene, 
as well as the partially hydrogenated homopolymers of butadiene and 
isoprene and copolymers of isoprene/divinylbenzene. 
Viscosity modifiers that function as dispersant viscosity modifiers also 
may be used. Descriptions of how to make such dispersant viscosity 
modifiers are found, for example, in U.S. Pat. Nos. 4,089,794, 4,160,739, 
and 4,137,185. Other dispersant viscosity modifiers are copolymers of 
ethylene or propylene reacted or grafted with nitrogen compounds such as 
described in U.S. Pat. Nos. 4,068,056, 4,068,058, 4,146,489 and 4,149,984. 
Antiwear and antioxidant agents which may be incorporated in the 
lubricating oil composition include, for example, dihydrocarbyl 
dithiophosphate metal salts, wherein the metal may be an alkali or 
alkaline earth metal, or zinc, aluminum, lead, tin, molybdenum, manganese, 
nickel or copper. The zinc salts are most commonly used in lubricating oil 
compositions in amounts of from about 0.1 to about 10, preferably about 
0.2 to about 2 wt. %, based upon the total weight of the lubricating oil 
composition. The salts may be prepared in accordance with known techniques 
by first forming a dihydrocarbyl dithiophosphoric acid (DDPA), usually by 
reaction of one or more alcohols or a phenol with P.sub.2 S.sub.5 and then 
neutralizing the formed DDPA with a zinc compound. The zinc dihydrocarbyl 
dithiophosphates can be made from mixed DDPA which in turn may be made 
from mixed alcohols. Alternatively, multiple zinc dihydrocarbyl 
dithiophosphates can be made and subsequently mixed. 
Preferred zinc dihydrocarbyl dithiophosphates useful in the present 
invention are oil soluble salts of dihydrocarbyl dithiophosphoric acids 
wherein the hydrocarbyl moieties may be the same or different hydrocarbyl 
radicals containing from 1 to 18, preferably 2 to 12, carbon atoms and may 
comprise radicals such as alkyl, alkenyl, aryl, aralkyl, alkaryl and 
cycloaliphatic radicals. Particularly preferred hydrocarbyl radicals are 
alkyl groups of 2 to 8 carbon atoms, including, for example ethyl, 
n-propyl, n-butyl, i-butyl, amyl, n-hexyl, n-octyl, and 2-ethylhexyl. In 
order to obtain oil solubility, the total number of carbon atoms in the 
dithiophosphoric acid will generally be about 5 or greater. When used in 
the present composition, the amount of dihydrocarbyl dithiophosphate metal 
salt should be limited such that the fully formulated motor oil contains 
less than about 0.1 wt. % phosphorus, preferably less than about 0.08 wt. 
% phosphorus, and more preferably less than about 0.06 wt. % phosphorus. 
Supplemental dispersants, i.e., dispersants that do not contain nitrogen, 
may be used. These nitrogen free dispersants may be esters made by 
reacting any of the functionalized oil soluble polymeric hydrocarbon 
backbones described above with hydroxy compounds such as monohydric and 
polyhydric alcohols or with aromatic compounds such as phenols and 
naphthols. Polyhydric alcohols are preferred, e.g. ethylene glycol or 
other alkylene glycols in which the alkylene radical contains from 2 to 
about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, 
glycerol monostearate, pentaerythritol, dipentaerythritol, and mixtures 
thereof. 
The ester dispersants also may be derived from unsaturated alcohols such as 
allyl alcohol. Still other classes of the alcohols capable of yielding 
nitrogen free ashless dispersants comprise ether-alcohols including, for 
example, oxy-alkylene and oxy-arylene-ether alcohols. They are exemplified 
by ether-alcohols having up to about 150 oxy-alkylene radicals in which 
the alkylene radical contains from 1 to 8 carbon atoms. 
The ester dispersants may be prepared by one of several known methods as 
illustrated for example in U.S. Pat. No. 3,381,022. The ester dispersants 
also may be borated, similar to the nitrogen containing dispersants, as 
described above. 
Oxidation inhibitors also may be included in the lubricating oil 
composition. Oxidation inhibitors reduce the tendency of mineral oils to 
deteriorate in service, which deterioration can be evidenced by the 
products of oxidation such as sludge and varnish-like deposits on engine 
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 sulfide, ashless oil soluble phenates and sulfurized phenates, 
phosphosulfurized or sulfurized hydrocarbons, metal thiocarbamates, oil 
soluble copper compounds such as those described in U.S. Pat. No. 
4,867,890, and molybdenum containing compounds such as molybdenum octoate 
(2-ethyl hexanoate), molybdenum dithiocarbamates, molybdenum 
dithiophosphates, oil-soluble molybdenum xanthates and thioxanthates, and 
oil-soluble molybdenum- and sulfur-containing complexes. 
In one aspect of the invention the lubricating oil composition may include 
at least about 0.05 wt. % of a sulfurized alkyl phenol or hindered phenol 
antioxidant. Generally, hindered phenols are oil soluble phenols 
substituted at one or both ortho positions. Other or additional 
antioxidants which may be used in the present compositions are disclosed 
in U.S. Pat. No. 5,232,614. 
Friction modifiers may be included in the lubricating oil composition to 
improve fuel economy. Among the well known friction modifiers which can be 
used are esters formed by reacting carboxylic acids and anhydrides with 
alkanols. Other conventional friction modifiers generally consist of a 
polar terminal group (e.g. carboxyl or hydroxyl) covalently bonded to an 
oleophilic hydrocarbon chain. Esters of carboxylic acids and anhydrides 
with alkanols are describe in U.S. Pat. Nos. 4,702,850 and 5,232,614. 
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 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 nonionic 
polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, and 
anionic alkyl sulfonic acids may be used in the present lubricating oil 
composition. 
Copper and lead bearing corrosion inhibitors may be used, but are typically 
not required with the composition of the present invention. 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. 2,719,126, and 
3,087,932 are typical. Other suitable corrosion inhibiting materials are 
disclosed in U.S. Pat. No. 5,232,614. When these compounds are included in 
the lubricating composition, they preferably are present in an amount not 
exceeding 0.2 wt % active ingredient. 
Foam control can be provided by many compounds including an anitfoamant of 
the polysiloxane type, for example, silicone oil or polydimethyl siloxane. 
A small amount of a demulsifying component may be used. A preferred 
demulsifying component can be obtained by reacting an alkylene oxide with 
an adduct obtained by reacting a bis-epoxide with a polyhydric alcohol 
(see, EP 330,522). The demulsifier should be used at a level not exceeding 
0.1 wt. % (A.I.). A treat rate of 0.001 to 0.05 wt. % is convenient. 
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 lubricating oil compositions are C.sub.8 
to C.sub.18 dialkyl fumarate/vinyl acetate copolymers and 
polyalkylmethacrylates. 
Some of the above-mentioned additives can provide a multiplicity of 
effects. For example, a single additive may act as a dispersant-oxidation 
inhibitor. This approach to lubricating oil formulating is well known and 
does not require further elaboration. 
The various components may be incorporated into a base oil in any 
convenient way. For example, 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. 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 that is subsequently 
blended into basestock to make finished lubricant compositions. Use of 
such concentrates is conventional. The concentrate typically will 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 lubricating oil. 
Preferably the concentrate is made in accordance with the method described 
in U.S. Pat. No. 4,938,880. That patent describes making a premix of 
ashless dispersant and metal detergents that is pre-blended at a 
temperature of at least about 100.degree. C. Thereafter the pre-mix is 
cooled to at least 85.degree. C. and the additional components are added. 
Such a concentrate typically comprises the following additives: 
______________________________________ 
Wt. % (A.I.) 
Wt. % (A.I.) 
ADDITIVE (Broad) (Preferred) 
______________________________________ 
Nitrogen containing Ashless 
10-40 20-30 
Dispersant(s) 
Overbase calcium detergent 
.05-20 .1-12 
Overbase magnesium detergent 
.05-20 .1-12 
Overbase sodium detergent 
.05-20 .1-15 
Neutral soap detergent 
0-25 .05-5 
Supplemental metal detergents 
0-20 1 
Corrosion inhibitor 
0-1 0 
Metal Dithiophosphate 
0-10 0-8 
Supplemental anti-oxidant 
0-40 0-30 
Anti-foaming agent .005-.02 .005-.01 
Supplemental anti-wear agents 
0-10 0.5 
Friction modifier 0-10 0.5 
Demulsifier 0-.1 0-.05 
Mineral or synthetic base oil 
balance balance 
Included in the final formulation 
Viscosity index improver 
.01-6 .01-4 
Pour point depressant 
.01-5 .01-1.5 
______________________________________ 
The final formulations may employ from 3 to 50 wt. % and preferably about 4 
to 20 wt. %, e.g., about 4 to 15 wt. % of the additive package(s) with the 
remainder being base oil. A preferred concentrate contains at least one 
ashless nitrogen containing dispersant, at least one calcium salt of an 
oil soluble acid having a TBN in excess of about 100, (preferably in 
excess of about 200, and more preferably in excess of about 300), at least 
one magnesium salt of an oil soluble acid having a TBN in excess of about 
100 (preferably in excess of about 200, and preferably in excess of about 
300), at least one sodium salt of an oil soluble acid having a TBN in 
excess of about 100 (preferably in excess of about 200, and preferably in 
excess of about 300), and at least one neutral soap. 
The lubricating oil composition of this invention is capable of decreasing 
engine deposits to the extent that less than 30 mg total deposits are 
observed when the composition is tested in accordance with the 
Thermo-Oxidation Engine Oil Simulation Test (TEOST). Preferred 
compositions in accordance with this invention result in less than 20 mg 
total deposits, and typically less than 15 mg total deposits being 
observed. The compositions of this invention are particularly well suited 
for use as passenger car motor oils (PCMO's), and can be formulated in a 
variety of grades. Particularly useful are single grade and multigrade 
oils of 0W to 50W, including permutations and combinations thereof, e.g., 
0W, 5W, 10W, 20W, etc., 0W20, 5W20, 10W30, 20W50, etc. 
The invention is further described, by way of illustration only, in the 
following examples. Unless otherwise noted, all treat rates of all 
additives are reported as wt.% active ingredient. 
Example 1 
A series of crankcase lubricant formulations (candidate oils) were prepared 
by blending with a base oil of lubricating viscosity the additives set 
forth in Table 1. The various candidate oils were identical, except for 
the metal detergent component(s). The phosphorus content of each of the 
candidate oils was from about 0.09 to 0.1 wt. %, based on the weight of 
the fully formulated oils. 
Each of the candidate oils was subjected to the Thermo-Oxidation Engine Oil 
Simulation Test (TEOST), as described in SAE 932837. During the 
approximately 2 hour test each candidate oil was circulated at a rate of 
0.49 ml/min from a 116 ml reactor through the annulus of a depositor rod 
having a filled depositor volume of approximately 0.8 ml. The reactor was 
held at 100.degree. C. during the entire test period, and the depositor 
rod was heated through 12 cycles according to the following program 
schedule: 
______________________________________ 
Program Step Temperature Time 
______________________________________ 
0 Ramp to 200.degree. C. 
Immediate 
1 Hold at 200.degree. C. 
1 minute 15 sec 
2 Ramp to 480.degree. C. 
1 minute 
3 Hold at 480.degree. C. 
2 minutes 
4 Ramp to 200.degree. C. 
4 minutes 
5 Hold at 200.degree. C. 
1 minute 15 sec 
______________________________________ 
Cycle 1 went through steps 0-5 once, cycles 2-12 went through steps 1-5 
eleven times. Each cycle took 9.5 minutes and the total test time was 114 
minutes. 
The apparatus used for the TEOST included the reactor which held the 
candidate oil, a gear pump, a high temperature (depositor) zone, and a 
disc-type oil filter. Oil in the reactor was continuously stirred and the 
temperature was monitored by the thermocouple. The depositor rods were 
made of 1018 steel having a finely finished surface. The primary source of 
heat to the depositor rods and the candidate oil within the casing/rod 
annulus was low-voltage, high-amperage resistive heating applied to the 
ends of the depositor rods. The materials used for each test run were the 
candidate oil, 100 ppm iron naphthenate oxidation catalyst added to the 
candidate oil, air (flowed into the reactor at rate of 3.6 ml/min through 
water) and N.sub.2 O (flowed into the reactor at a rate of 3.6 ml/min 
through water). After completion of each 12 cycle test run, the deposits 
that were formed on the depositor rod were weighed to within 0.1 mg. The 
deposits that were formed, but which did not adhere to the depositor rod, 
or which came loose during each test run, were trapped on the oil filter. 
The trapped filter deposits also were weighed to within 0.1 mg. For a 
given test run to pass the TEOST, the total weight of the collected 
deposits must be less than 60 mg. For each test run, the weight of the rod 
deposits, the weight of the filter deposits, and the total weight of the 
rod deposits plus the filter deposits are shown in Table 1. 
__________________________________________________________________________ 
Run No. Wt. % 
Component 1 2 3 4 5 6 7 
__________________________________________________________________________ 
Mg sulphonate 
0.63 
0 0 0.31 
0.31 
0 0.21 
detergent.sup.1 
Ca sulphonate 
0 0.63 
0 0 0.31 
0.31 
0.21 
detergent.sup.2 
Na sulphonate 
0 0 0.63 
0.31 
0 0.31 
0.21 
detergent.sup.3 
Dispersant.sup.4 
2.8 2.8 2.8 2.8 2.8 2.8 2.8 
Diluent oil 10.61 
10.61 
10.61 
10.61 
10.61 
10.61 
10.61 
Neutral soap.sup.5 
0.14 
0.14 
0.14 
0.14 
0.14 
0.14 
0.14 
Silicone 0.002 
0.002 
0.002 
0.002 
0.002 
0.002 
0.002 
antifoamant 
Friction modifier 
0.15 
0.15 
0.15 
0.15 
0.15 
0.15 
0.15 
Antioxidant 0.85 
0.85 
0.85 
0.85 
0.85 
0.85 
0.85 
Zinc dialkyldithiophosphate 
0.86 
0.86 
0.86 
0.86 
0.86 
0.86 
0.86 
Pour point depressant 
0.08 
0.08 
0.08 
0.08 
0.08 
0.08 
0.08 
Demulsifier 0.004 
0.004 
0.004 
0.004 
0.004 
0.004 
0.004 
Viscosity index improver 
0.5 0.5 0.5 0.5 0.5 0.5 0.5 
Mineral basestock 
82.65 
82.65 
82.65 
82.65 
82.65 
82.65 
82.65 
TEOST DEPOSITS (mg) 
Rod 16.0 
14.1 
11.5 
10.5 
16.6 
11.7 
7.9 
Filter 4.1 4.0 4.4 5.2 2.6 8.3 1.5 
Total 20.1 
18.1 
15.9 
15.7 
19.2 
20.0 
9.4 
__________________________________________________________________________ 
.sup.1 = 400 TBN Mg sulphonate 
.sup.2 = 400 TBN Ca sulphonate 
.sup.3 = 400 TBN Na sulphonate 
.sup.4 = Polyisobutenyl succinimide; PIB Mn = 2225; 
.sup.5 = 24 TBN soap 
As can be seen from the data in Table 1, all of the candidate oils resulted 
in less than 60 mg total deposits. Accordingly, all of the oils achieved 
acceptable (passing) TEOST results . However, it was found that the 
candidate oil containing the Mg-Ca-Na tri-metal detergent mixture (Run No. 
7) resulted in by far the least rod deposits, by far the least filter 
deposits, and by far the least total deposits. When compared to the 
results observed for the candidate oils containing only one metal 
detergent (Run Nos. 1-3) or any bi- metal detergent mixture (Run Nos. 
4-6), the vastly superior results observed for the tri-metal detergent 
mixture were quite unexpected. 
FIG. 2 illustrates the results of the various runs in Example 1 on a 
triangular graph, wherein the percentage of the total TBN of the 
lubricating oil composition contributed by the sodium overbased detergent 
is shown on the left-hand axis, the percentage of the total TBN 
contributed by the calcium overbased detergent is shown on the right-hand 
axis, and the percentage of the total TBN contributed by the magnesium 
overbased detergent is shown on the bottom axis. The numbers in each 
square on the graph represent the total deposits observed for that 
particular run. 
Example 2 
A crankcase lubricant formulation (candidate oil) was prepared by blending 
the additives set forth in Table 2 with a base oil of lubricating 
viscosity. The candidate oil was subjected to the CATERPILLAR 1M-PC test, 
which is used for determining the effects of lubricating oils on ring 
sticking, ring and cylinder wear and accumulation of piston deposits. The 
test method is designed to relate to high speed, supercharged diesel 
engine operation, and, in particular, to the detergency characteristics 
and anti-wear properties of diesel crankcase lubricating oils. The test 
operation involved the control of a supercharged, single-cylinder diesel 
test engine for a total of 120 hours at a fixed speed and fuel rate using 
the candidate oil as a lubricant. A one hour break-in period preceded the 
test. At the conclusion of the test, the piston, rings, and cylinder were 
examined, and the amount and nature of the piston deposits were noted. For 
a candidate oil to pass this test, the observed top groove fill (TGF) 
demerits must be less than 70 mg and the observed weighted total demerits 
(WTD) must be less than 240 mg. As shown in Table 2, the candidate oil 
resulted in an observed TGF of only 67 mg and an observed TWD of only 145 
mg. Accordingly, the candidate oil passed the 1M-PC test. 
TABLE 2 
______________________________________ 
Component Wt % (A.I.) 
______________________________________ 
Mg sulphonate detergent.sup.1 
0.21 
Ca sulphonate detergent.sup.2 
0.21 
Na sulphonate detergent.sup.3 
0.21 
Dispersant.sup.4 2.88 
Diluent oil 5.4 
Neutral soap.sup.5 0.14 
Silicone antifoarnant 
0.002 
Friction modifier 0.15 
Antioxidant 0.85 
Zinc dialkyldithidphosphate 
0.86 
Pour point depressant 
0.09 
Demulsifier 0.004 
Viscosity index improver 
0.54 
Mineral basestock 88.45 
OBSERVED RESULTS 
TGF (&lt;70 passes) 67 
TWD (&lt;240 passes) 145 
______________________________________ 
.sup.1 400 TBN Mg sulphonate 
.sup.2 400 TBN Ca sulphonate 
.sup.3 400 TBN Na sulphonate 
.sup.4 Polyisobutenyl succinimide; PIB Mn = 2225; 
.sup.5 24 TBN soap 
Example 3 
Three lubricating oil compositions were evaluated for valve train wear 
performance utilizing a 2.3 L inline 4 cylinder engine equipped an 
overhead cam sliding follower valve train. The oil compositions were 
identical, except that the first composition contained only a magnesium 
overbased detergent, the second contained only a calcium overbased 
detergent, and the third contained only a sodium overbased detergent. The 
results of the evaluation, which are set forth below in Table 3, 
demonstrate that the oil composition containing the magnesium overbased 
detergent resulted in improved wear performance. 
TABLE 3 
______________________________________ 
Detergent Type Valve Train Wear, mils. 
______________________________________ 
Magnesium Overbased 
7.0 
Calcium Overbased 
8.5 
Sodium Overbased 
9.5 
______________________________________