Abstract: A lubricating composition comprises a base oil and between 10 ppm and 1000 ppm by mass of a viscosity modifier, the viscosity modifier comprising a polymer having a number average molecular weight greater than 500,000. The polymer's side-chains may be branched or unbranched. The polymer is preferably selected from the group consisting of polyolefin, poly alpha olefin, poly internal olefin, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, ethylene-propylene-acrylate copolymers, ethylene-propylene-methacrylate copolymers, ethylene-propylene-aromatic copolymers, ethylene-propylene-diene-acrylate copolymers, ethylene-propylene-diene-methacrylate copolymers, and combinations thereof.

Abstract: A lubricating oil composition comprising:(a) from 0.01 to 10 percent by weight of a dispersant viscosity index improver linear diblock copolymer or a radial or star copolymer with each arm having an overall number average molecular weight of 7500 to 250,000 and comprising a block of a conjugated diene having a number average molecular weight of 5000 to 200,000 and a block of a vinyl aromatic hydrocarbon having a number average molecular weight of 2500 to 100,000, and a vinyl aromatic hydrocarbon content of 5 to 50 weight percent, wherein from 5 to 10 N-vinyl imidazole functional groups per molecule have been grafted onto the copolymer;(b) from 5 to 20 percent by weight of a dispersant inhibitor package containing 40 percent by weight less ashless dispersant than is required for use with a non-dispersant viscosity index improver; and(c) from 80 to 95 percent by weight of a base oil.

Abstract: Block polymers of the star type contain a central core of crosslinked bisunsaturated compound and a plurality of functionalized branches attached to the core, each branch containing at least a terminal portion of polymerized alkyl methacrylate, polymerized through the ethylenic unsaturation of the methacrylate moiety. The polymers are useful in adhesive formulations and as viscosity index improvers for hydrocarbon fluids.