Multifunctional viscosity index improver derived from amido-amine and

Abstract

Composition of matter useful as multifunctional viscosity index improver for lubricating oil comprising reaction product of: (i) (a) molecular weight degraded ethylene-alpha-olefin copolymer obtained by degrading copolymer of ethylene and at least one other alpha-olefin monomer, said copolymer comprising intramolecularly heterogeneous copolymer chains containing at least one crystallizable segment of methylene units and at least one low crystallinity ethylene-alpha-olefin copolymer segment, wherein said copolymer has a molecular weight distribution characterized by at least one of a ratio of M.sub.w /M.sub.n of less than 2 and a ratio of M.sub.z /M.sub.w of less than 1.8, and said degraded copolymer grafted with (b) ethylenically monounsaturated carboxylic acid material having 1 to 2 carboxylic acid groups or anhydride group to form grafted ethylene copolymer; (ii) about C.sub.50 to about C.sub.400 hydrocarbyl substituted carboxylic acid component containing 1 to 2 carboxylic acid groups or anhydride group; (iii) thioamido-amine; and (iv) C.sub.12 to about C.sub.18 hydrocarbyl substituted dicarboxylic anhydride.