Abstract: 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.

Abstract: The present invention is directed to a method to clean up or keep clean the fuel system of a direct injection spark-ignited engine by operating the engine with a fuel composition that includes a liquid fuel and a fuel additive composition. The fuel additive composition useful in the present invention has at least one nitrogen-containing dispersant and optionally a fluidizer where the dispersant has a specific lipophilic parameter and the dispersant or the dispersant and the fluidizer have a specific hydrophilic-lipophilic parameter, the dispersant provides about 0.15 to about 50 ppm by weight nitrogen in the fuel composition, and the fluidizer and/or the dispersant provide about 10 to about 10,000 ppm by weight active components in the fuel composition. The method of the present invention is effective in controlling deposits in fuel injectors and combustion chambers of a direct injection spark-ignited engine.

Abstract: In a method of operating an internal combustion engine, a nitrogen-containing detergent composition is introduced into a combustion chamber of the engine wherein the detergent composition can improve the performance of both a fuel composition and a lubricating oil of the engine. The detergent composition contains (A) a reaction product of a hydrocarbyl-substituted acylating agent and an amine, (B) a hydrocarbyl-substituted amine, (C) a Mannich reaction product, (D) a high molecular weight polyetheramine, or (E) a mixture thereof.

Abstract: 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.

Abstract: A fuel additive composition comprising at least one amine, whereun said at least one amine contains at least one polyolefin group and at least one polyetheramine. These compositions are useful as fuel additives for reducing intake valve deposits. In addition, these compositions do not contribute to an increase in combustion chamber deposits in port fuel injected internal combustion engines.