Timken and Four-ball Machine tests were used to study the effects of the dodecyl amine salt of benzotriazole (ASBT) on the lubricity of liquid paraffin containing sulfurized olefin (SO). The wear rate and friction coefficient decreased in the presence of ASBT. The tribochemical reactions of both ASBT and SO were studied with the aid of modern physical techniques, such as AES, ESCA, IR spectroscopy and scanning electron microscopy.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Hartford, Connecticut, October 18–20, 1983