| abstract |
The present invention is directed to a viscosity index improver for lubricating oil compositions comprising the reaction product of A) a copolymer of ethylene and at least one other alpha-olefin monomer, said copolymer grafted with ethylenically monounsaturated carboxylic acid material and B) amido-amine or thioamido-amine comprising the reaction product of a polyamine and alpha, beta-unsaturated compound of the formula <IMAGE> wherein X is oxygen or sulfur, Y is OR4, -SR4 or <IMAGE> and R1, R2, R3, R4 and R5 are independently selected from hydrogen, hydrocarbyl and substituted hydrocarbyl. |