Abstract: An additive for use with fuel oils, in particular, automotive diesel fuel, consists essentially of a hydrocarbon petroleum distillate, and, in particular, kerosene; an aromatic hydrocarbon solvent and an anhydrous lower aliphatic ether. The ether, which is employed herein, is, preferably, ethyl ether and the aromatic hydrocarbon is, preferably, xylene. Minor amounts of the additive are mixed with the diesel fuel to enhance the efficiency thereof.