Quaternized nitrogen compounds and use thereof as additives in fuels and lubricants

A method for modifying a fuel composition comprising adding a reaction product or a quaternized nitrogen compound obtained from the reaction product to a fuel in an amount sufficient to modify the fuel, wherein said reaction product is produced by a process comprising

• a. reacting a hydrocarbyl-substituted polycarboxylic acid compound with a compound comprising at least one nitrogen group capable of an addition reaction with the polycarboxylic acid, and comprising at least one quaternizable amino group, to obtain a quaternizable hydrocarbyl-substituted polycarboxylic acid compound, and
• b. reacting the product of a) with a quaternizing agent which converts the at least one quaternizable amino group to a quaternary ammonium group, said quaternizing agent being the alkyl ester of salicylic acid;
• or
• reacting a quaternizable hydrocarbyl-substituted polycarboxylic acid compound comprising at least one quaternizable amino group with a quaternizing agent which converts the at least one quaternizable amino group to a quaternary ammonium group, said quaternizing agent being the alkyl ester of salicylic acid,
• wherein about 1.1 to about 2.0 equivalents of quaternizing agent are used per equivalent of quaternizable tertiary nitrogen atom.