Patent ID: 8668749

Claim:
A method for improving the performance of an engine combusting a diesel fuel having 50 ppm by weight or less sulfur, said method comprising: combining a low sulfur middle distillate fuel with a fuel additive comprising a reaction product of (a) a hydrocarbyl-substituted acylating agent and (b) a reactant selected from the group consisting ethylenediamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, ammonia, aminoguanidine bicarbonate, guanidine, piperazine, methylpiperazine, amino-pyrimidine, aminotriazole, and aminotetrazole, C 2 -C 3 -alkanolamines, N-ethanol-ethylenediamine, hydroxyethyl pyridine, water, and mixtures thereof that provides at least 10 molar percent of reaction product based on total moles of the reaction product, said reaction product selected from the group consisting of (1) a mono-amide/mono-acid or a mono-amide/metal free mono-acid salt thereof, and (2) monoester/mono-acid or a monoester/metal free mono-acid salt thereof, wherein the reaction product is made under conditions sufficient to provide the reaction product with at least 10 molar percent acid groups or nitrogen-containing salt thereof based on total moles of the reaction product; and combusting the additized fuel in the engine, whereby the performance of the engine is improved relative to the performance of the engine in the absence of the fuel additive.