A lubricating oil composition may contain a base oil (A) and a dispersant-type viscosity index improver (B), in which the nitrogen atom content based on the solid content of the dispersant-type viscosity index improver (B) is 0.50 to 1.50% by mass, and the weight-average molecular weight (Mw) thereof is 100,000 or more, and the content in terms of the solid content based on the total amount of the composition of the dispersant-type viscosity index improver (B) is more than 0.05% by mass and less than 5.0% by mass. The lubricating oil composition may exert excellent wear resistance in a state contaminated with soot.

A lubricating oil composition may contain a base oil (A) and a dispersant-type viscosity index improver (B), in which the nitrogen atom content based on the solid content of the dispersant-type viscosity index improver (B) is 0.50 to 1.50% by mass, and the weight-average molecular weight (Mw) thereof is 100,000 or more, and the content in terms of the solid content based on the total amount of the composition of the dispersant-type viscosity index improver (B) is more than 0.05% by mass and less than 5.0% by mass. The lubricating oil composition may exert excellent wear resistance in a state contaminated with soot.

This disclosure describes an ashless lubricant additive. The additive is a tertiary amine-containing compound having the following structure:

##STR00001##

where R.sup.1 and R.sup.2 are independently a linear or branched-chain monovalent hydrocarbyl group having two to about twenty carbon atoms, each m is independently from 0 to 2, each p is independently from 0 to 2, for each cyclic moiety m+p is from 2 to 4, and each n is independently from 1 to 6.

This disclosure describes an ashless lubricant additive. The additive is a tertiary amine-containing compound having the following structure:

##STR00001##

where R.sup.1 and R.sup.2 are independently a linear or branched-chain monovalent hydrocarbyl group having two to about twenty carbon atoms, each m is independently from 0 to 2, each p is independently from 0 to 2, for each cyclic moiety m+p is from 2 to 4, and each n is independently from 1 to 6.

There is provided a lubricating oil composition which is excellent in the wear resistance and the oil film retention even when the viscosity of the composition is lowered. The lubricating oil composition comprises: a base oil (A); an imide compound (B); a calcium-based detergent (C); a polymer component (D); and a zinc dithiophosphate (E), wherein the imide compound (B) comprises at least one non-boron-modified succinic acid imide compound (Bx) selected from a succinic acid monoimide (B1x) represented by general formula (b-1) and a succinic acid bisimide (B2x) represented by general formula (b-2), and wherein the polymer compound (D) has a mass average molecular weight (Mw) of not less than 10,000 and not more than 50,000, and comprises at least one selected from an olefin polymer (D1) and a polymethacrylate (D2).

There is provided a lubricating oil composition which is excellent in the wear resistance and the oil film retention even when the viscosity of the composition is lowered. The lubricating oil composition comprises: a base oil (A); an imide compound (B); a calcium-based detergent (C); a polymer component (D); and a zinc dithiophosphate (E), wherein the imide compound (B) comprises at least one non-boron-modified succinic acid imide compound (Bx) selected from a succinic acid monoimide (B1x) represented by general formula (b-1) and a succinic acid bisimide (B2x) represented by general formula (b-2), and wherein the polymer compound (D) has a mass average molecular weight (Mw) of not less than 10,000 and not more than 50,000, and comprises at least one selected from an olefin polymer (D1) and a polymethacrylate (D2).

The invention relates to a lubricant composition comprising at least: a base oil, a friction modifier comprising molybdenum, a boron-containing dispersant, a polymer comprising repeating units which can be obtained by polymerization of monomers (a) with the formula (I):

##STR00001## wherein: R1 represents a hydrogen atom or a methyl moiety, X1 represents a moiety chosen from: O, O(AO)m, or NH, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10. R2 is a polybutylene moiety, and p is equal to 0 or 1.

The invention relates to a lubricant composition comprising at least: a base oil, a friction modifier comprising molybdenum, a boron-containing dispersant, a polymer comprising repeating units which can be obtained by polymerization of monomers (a) with the formula (I):

##STR00001## wherein: R1 represents a hydrogen atom or a methyl moiety, X1 represents a moiety chosen from: O, O(AO)m, or NH, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10. R2 is a polybutylene moiety, and p is equal to 0 or 1.

Improved organic anti-wear additive compositions are disclosed containing certain citric acid esters, e.g., mixtures comprising citrate oligomers, and fatty acid alkanolamides. The combination exhibits excellent and synergistic anti-wear activity in lubricants. The compositions of the invention beneficially allow one to reduce amounts of zinc and phosphorus that are often used in lubricants, while boosting anti-wear performance and maintaining, and often enhancing, friction reduction properties.

The present invention relates to lubricant compositions for scooter engines and methods for reducing static friction between ferrous and non-ferrous surfaces as may be found in a wet clutch. The lubricant compositions contain polyether compounds in combination with one or more ash-free friction modifiers.