Mixed dispersants for lubricants

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 or the reactive equivalent thereof, wherein the polyisobutene-substituted succinic anhydride component comprises:

• (a) about 10 to about 95 weight percent of a component 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
• (b) about 5 to about 90 weight percent of a component 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;
• 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, Mn, of about 800 to about 2500;
• wherein the dispersant composition has a CO:N ratio of at least 0.9:1;
• said dispersant composition being free of glycerol monooleate.

A composition comprising an oil of lubricating viscosity and a mixture of dispersants, comprising a mixture of:

• (a) about 10 to about 95 weight percent of a dispersant 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 reacting the intermediate formed thereby with at least one alkylene polyamine having at least one N-H group;
• and
• (b) about 5 to about 90 weight percent of a dispersant 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, and reacting the intermediate formed thereby with at least one alkylene polyamine having at least one N-H group;
• wherein the polyisobutene substituents of components (a) and (b) independently have a molecular weight, Mn, of about 800 to about 2500;
• wherein the mixture of dispersants has a CO:N ratio of at least 0.9:1;
• said composition being free of glycerol monooleate.