Method of operating internal combustion engine by introducing antioxidant into combustion chamber

摘要

In a method of operating an internal combustion engine, an antioxidant composition is introduced into a combustion chamber of the engine. The antioxidant composition contains (A) a sterically hindered phenol; (B) an alkylene or alkylidene coupled sterically hindered phenol oligomer; (C) a secondary aromatic amine; (D) a reaction product of a hydrocarbyl-substituted hydroxy-containing aromatic compound, an aldehyde, and a carboxyl-substituted phenol; or (E) a mixture thereof. The method improves the performance of a lubricating oil of the engine.