Patent ID: 8415284

Claim:
A lubricating oil composition comprising: a major amount of oil of lubricating viscosity; and a minor amount of at least one olefin copolymer having a number average molecular weight greater than about 10,000 up to about 300,000, wherein the olefin copolymer is grafted with a grafting component substantially devoid of carboxylic functionalizing groups comprising (A) a vinyl-substituted aromatic compound, and (B) a compound selected from the group consisting of a C 5 -C 30 olefin, a polyalkylene compound, and mixtures thereof, wherein a mole ratio of A/B in the reaction mixture ranges from about 0.25:1 to about 5:1; and optionally, a minor amount of at least one non-grafted olefin copolymer, styrene-isoprene copolymer, methacrylate copolymer, or styrene butadiene copolymer have number average molecular weight greater than about 50,000 up to about 300,000, wherein the olefin copolymer has an ethylene content ranging from about 60 to about 85 mole percent of the olefin copolymer.