Abstract: A composition of the reaction product of (a) an isobutylene-diene copolymer having thereon groups containing carboxylic acid functionality or reactive equivalent thereof, derived from an ?,?-unsaturated carboxylic compound; and (b) an amine component comprising at least one aromatic amine containing at least one N—H group capable of condensing with said carboxylic acid functionality, is a useful dispersant viscosity modifier.

Abstract: A lubricant composition comprises (A) a major amount of an oil of lubricating viscosity and (B) a minor amount of a diblock copolymer comprising a poly(monovinyl aromatic hydrocarbon) block and a hydrogenated poly(conjugated diene) block where the diblock copolymer has a weight average molecular weight of 10,000 to 50,000 and a poly(monovinyl aromatic hydrocarbon) content of 5 to 45% by weight. A concentrate composition, a method for improving viscosity performance of a lubricant composition for an internal combustion engine, and a method for lubricating an internal combustion engine comprise the diblock copolymer which is especially useful for reducing soot-induced viscosity increase in a compression-ignited internal combustion engine equipped with an exhaust gas recirculation system.

Abstract: Reaction of a carboxylic acid-containing polymer with certain aromatic amines results in dispersant viscosity modifiers with improved soot handling performance in heavy-duty diesel engines, compared with reaction with non-aromatic amines.