Patent ID: 7615521

Claim:
A composition comprising an oil of lubricating viscosity and a dispersant composition comprising the product of (1) at least one alkylene polyamine having at least one N-H group with (2) a polyisobutene-substituted succinic anhydride component or the reactive equivalent thereof, wherein the polyisobutene-substituted succinic anhydride component comprises: (a) about 10 to 80 weight percent of a component wherein at least one succinic anhydride moiety is attached to the polyisobutene substituent through a cyclic linkage; and (b) 20 to about 90 weight percent of a component wherein at least one succinic anhydride moiety is attached to the polyisobutene substituent through a non-cyclic linkage; wherein at least one alkylene polyamine is reacted separately with the polyisobutene-substituted anhydrides of (a) and of (b) and the reaction products are mixed together in amounts corresponding to (a) and (b); wherein the polyisobutene substituents of components (a) and (b) independently have a molecular weight, M n , of about 800 to about 2500; wherein the dispersant composition has a CO:N ratio of at least 0.9:1; said composition being free of glycerol monooleate; wherein: the polyisobutene-substituted succinic anhydride component (a) is prepared by reacting a polyisobutylene, less than about 20 percent of the chains thereof containing a terminal vinylidene end group, with maleic anhydride in the presence of chlorine; and the polyisobutene-substituted succinic anhydride component (b) is prepared by reacting a polyisobutylene, at least about 70 percent of the chains thereof containing a terminal vinylidene end group, with maleic anhydride in the substantial absence of chlorine.