(57) It is known to use chlorinated paraffins as an extreme pressure lubricant additive in lubricating metals. Such additives are highly corrosive, however, and for that reason are not suitable for a number of uses, such as in the lubrication of internal combustion engines. The present invention overcomes the corrosive problems of the previous chlorinated paraffin additives. The present invention involves the mixing of a substantial portion of chlorinated paraffins with a smaller portion of an alkaline earth metal sulfonate, such as calcium or barium sulfonate, and preferably a base mineral oil and solvent The resulting additive can be added to standard motor oil to improve its extreme pressure performance in internal combustion engines.