Viscosity modifiers for lubricant compositions

A vehicle having moving parts and containing a lubricant for lubricating the moving parts, the lubricant comprising an oil of lubricating viscosity and from about 5 to about 30 percent by weight of an additive comprising a shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, and wherein the amount of additive in the lubricant is based on a total weight of the lubricant.

A fully formulated lubricant composition comprising a base oil component of lubricating viscosity and from about 5 to about 30 percent by weight of an additive comprising a shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, and wherein the amount of additive in the lubricant composition is based on a total amount of lubricant composition.

A method for improving the viscosity index of a lubricant composition comprising mixing with the lubricant composition from about 5 to about 30 percent by weight of an additive comprising a shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, and wherein the amount of shear stable olefin copolymer in the lubricant composition is based on a total weight of the lubricant composition.

A lubricant additive concentrate comprising a diluent or carrier oil and from about 5 to about 90 percent by weight of an additive comprising a shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, and wherein the amount of shear stable olefin copolymer in the lubricant composition is based on a total weight of the additive concentrate.

A method of lubricating moving parts of a vehicle, the method comprising using as a lubricating oil for one or more moving parts of the vehicle a lubricant composition containing a base oil and a lubricant additive, the lubricant additive comprising a diluent or carrier oil and an amount of shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000 sufficient to provide from about 5 to about 30 weight percent of the shear stable olefin copolymer in the lubricant composition, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, and wherein the amount of shear stable olefin copolymer in the lubricant composition is based on a total weight of the lubricant composition.

A method of lubricating moving parts comprising contacting the moving parts with a lubricant composition containing a lubricant additive, the lubricant additive comprising a diluent or carrier oil and from about 5 to about 95 percent by weight of a shear stable olefin copolymer derived from a copolymer having a number average molecular weight ranging from about 50,000 to about 250,000, wherein the shear stable olefin copolymer has a shear stability index of less than about 40, a polydispersity of not more than about 1.5, and a thickening efficiency of greater than about 1.8, wherein the lubricant composition contains from about 5 to about 30 percent by weight of the additive based on a total weight of the lubricant composition.