Dispersant anti-oxidant VI improver and lubricating oil composition containing same

A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount effective to impart viscosity index, dispersancy, and antioxidant properties to said oil of an additive composition prepared by reacting a polymer prepared from ethylene and at least one C.sub.3 -C.sub.10 alpha-monoolefin and optionally a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of said C.sub.3 -C.sub.10 alpha-monoolefin and from about 0 to 15 mole percent of said polyene and having an average molecular weight ranging from about 5,000 to 500,000 with a nitrosodiphenylamine compound represented by the formula:

• ##STR5## in which R and R' represent hydrogen or an organic radical having from 1 to 10 carbon atoms.