Oil-soluble viscosity index-improving ethylene copolymers, such as copolymers of ethylene and propylene; and ethylene, propylene and diolefin; etc., are maleic anhydride, and the maleic anhydride is maintained below its solubility limit during grafting. The grafted product may be reacted with polyamines having two or more primary amine groups and a carboxylic acid component, preferably alkylene polyamine and alkenyl succinic anhydride, such as polyisobutenyl succinic anhydride; or the grafted ethylene copolymer can be reacted with already formed salts, amides, imides, etc. of said polyamine and acid component, preferably imides of alkylene polyamine and alkenyl succinic anhydride. The grafting reaction gives products with improved haze performance.