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Oil-soluble, derivatized ethylene copolymers derived from about 2 to 98 wt. % ethylene, and one or more C3 to C28 alpha-olefins, e.g. propylene, which are grafted, preferably solution-grafted under an inert atmosphere and at elevated temperatures and in the presence of a high-temperature decomposabl

Oil-soluble, derivatized ethylene copolymers derived from about 2 to 98 wt. % ethylene, and one or more C3 to C28 alpha-olefins, e.g. propylene, which are grafted, preferably solution-grafted under an inert atmosphere and at elevated temperatures and in the presence of a high-temperature decomposable free-radical initiator, with an ethylenically-unsaturated dicarboxylic acid material and thereafter reacted with a polyamine having at least two primary amine groups, e.g. an alkylene polyamine such as diethylene triamine, to form carboxyl-grafted polymeric imide, usually maleimide, derivatives are reacted with an anhydride of a C1-C30 hydrocarbyl substituted acid, preferably acetic anhydride, to yield an oil-soluble stable amide of said polyamine whereby oil solutions of said amide derivative are characterized by minimal viscosity change over an extended period of time. Useful number average molecular weight (Mn) of said copolymers range from about 700 to 500,000; however, if the molecular weight is from 10,000 to 500,000 then these copolymers are also useful as multifunctional viscosity index improvers.

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A lubricating oil composition comprising a major amount of a lubricating oil having dissolved therein at least a viscosity index improving amount of an oil-soluble ethylene polymeric viscosity index improver having dispersancy properties and containing in the range of from about 0.001 to 8 wt. % of

A lubricating oil composition comprising a major amount of a lubricating oil having dissolved therein at least a viscosity index improving amount of an oil-soluble ethylene polymeric viscosity index improver having dispersancy properties and containing in the range of from about 0.001 to 8 wt. % of nitrogen, which improver has been formed by: grafting an ethylene copolymer comprising about 30 to 80 wt. % ethylene and about 20 to 70 wt. % C3 to C28 alpha olefin, with an ethylenically unsaturated acid material selected from the group consisting of unsaturated carboxylic acids anD anhydrides of carboxylic acid, reacting said grafted ethylene copolymer with polyamine of 2 to 60 carbons and 2 to 12 nitrogens and having at least two primary amine groups, wherein essentially one of said primary amine groups reacts with an acid moiety of said grafted ethylene copolymer, and reacting with an anhydride of an acid having a C1 to C30 hydrocarbyl group to thereby stabilize the resulting ethylene polymeric viscosity index improver and inhibit viscosity increase of said oil composition upon aging.