Gasoline additive composition for improved engine performance

A method of reducing deposits in a gasoline engine, the method comprising:

• operating a gasoline engine on a fuel composition containing a major amount of a gasoline fuel and a minor amount of a fuel additive by injecting the gasoline fuel through one or more injectors;
• wherein the fuel additive includes (i) a Mannich detergent derived from the reaction product of a hydrocarbyl-substituted phenol or cresol, one or more aldehydes, and one or more alkylene polyamines;
• (ii) a succinimide detergent prepared by reacting a hydrocarbyl-substituted succinic acylating agent with an amine, polyamine, or alkyl amine having one or more primary, secondary, or tertiary amino groups;
• and (iii) wherein the fuel additive has a weight ratio of the Mannich detergent to the succinimide detergent of from about 20:1 to about 30:1;
• wherein the fuel additive reduces deposits in the gasoline engine;
• and
• wherein the Mannich detergent has the structure of Formula I:
• wherein R1 is hydrogen or a C1 to C4 alkyl group, R2 is a hydrocarbyl group having a molecular weight of about 500 to about 3000, R3 is a C1 to C4 alkylene or alkenyl group, and R4 is hydrogen, and R5 is a mono or di(C1 to C4)alkyl amino C1-C12 alkyl group;
• wherein the succinimide detergent is a hydrocarbyl substituted mono-succinimide detergent, a hydrocarbyl substituted bis-succinimide detergent, or a combination thereof;
• and wherein the hydrocarbyl-substituted succinic acylating agent is a hydrocarbyl-substituted succinic anhydride, wherein the hydrocarbyl group has a molecular weight of about 450 to about 3000, and wherein a molar ratio of the hydrocarbyl-substituted succinic anhydride to the amine, polyamine, or alkyl amine is from about 0.5:1 to about 2:1;
• and
• wherein the gasoline fuel composition includes about 55 to about 190 ppmw of the Mannich detergent, about 0.5 to about 20 ppmw of the succinimide detergent;
• and about 5 to about 150 ppmw of the alkoxylated alcohol.