Patent ID: 7407918

Claim:
A method of reducing wear in an internal combustion engine, comprising: using as the crankcase lubricating oil for said engine a lubricant composition comprising: a major amount of base oil; a first dispersant and a second dispersant each independently comprising at least one member selected from the group consisting of hydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines, and Mannich base adducts derived from hydrocarbyl-substituted phenols condensed with aldehydes and amines; wherein the hydrocarbyl substituent of the first dispersant has a number average molecular weight ranging from about 1500 to about 2500 as determined by gel permeation chromatography, wherein the hydrocarbyl substituent of the second dispersant has a number average molecular weight ranging from about 800 to about 1200 as determined by gel permeation chromatography, and wherein the hydrocarbyl-substituent of at least one of the first and second dispersants comprises a polymerization product derived from a reaction mixture comprising (i) from about 55 to about 65 weight percent raffinate I stream and (ii) from about 35 to about 45 weight percent isobutylene, with the proviso that (i) and (ii) are different; and a minor viscosity index improving amount of a non-shear stable viscosity index improver comprising a substantially linear block copolymer having a number average molecular weight as determined by gel permeation chromatography ranging from about 50,000 to about 250,000, the block copolymer being derived from a conjugated diene monomer containing no less than 5 carbon atoms and a styrene monomer, wherein the block copolymer has a styrene content ranging from about 30 wt. % to about 40 wt. %, and an olefinic unsaturation ranging from about 0.5 wt. % to about 5 wt. %.