PURPOSE: To provide a titled additive which saves fuel consumption and extends oil-exchange life, which consists of a sulfur-based oxidation inhibitor, a sulfonate- based cleaning agent, a nitrogen-based dispersing agent, a viscosity index improver, a Mo-based extreme-pressure additive, a polybutene-based stringiness improver, and others.

CONSTITUTION: An engine oil additive consists of (A) 0.5W15wt% of a sulfur- based oxidation inhibitor, (B) 0.5W15wt% of a sulfonate-based cleaning agent, (C) 0.5W15wt% of a nitrogen-based dispersing agent, (D) 0.1W5wt% of a zinc- or phosphorus-based abrasion resisting agent, (E) 0.5W15wt% of a viscosity index improver (polyolefin), (F) 0.1W5wt% of an amine-based pour point depressant, (G) 0.2W10wt% of an Mo-based extreme-pressure additive, (H) 0.5W15wt% of a polybutene-based stringiness improver, (I) a minute amount of a silicone-based defoamer, and (J) a minute amount of a mineral oil or modified mineral oil. By use of an additive composition comprising specific amounts of specific additives, the life of the oil is extended, engine output is increased, and fuel consumption is decreased.