| abstract |
A method of removing deposits from a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising an engine cleaning additive, wherein the engine cleaning additive is the product of a Mannich reaction between: (a) an aldehyde;(b)ammonia, hydrazine or an amine; and (c) an optionally substituted phenol;wherein the or each substituent of the phenol component (c) has an average molecular weight of less than 400. |