Lubricant or fuel compositions comprising 1) an organo, ring-substituted diphenyl sulfide, e.g. a monoalkyldiphenyl sulfide; 2) a dispersant component comprising at least one polymer-substituted succinimide, succinamide and/or succinic acid ester in which the alcohol or phenol moiety of the ester group may optionally contain amide, imide or amine nitrogen functionality, or mixtures of said amide, imide and/or ester; and 3) a dithiophosphate, e.g., a zinc dithiophosphate. The compositions have superior antiwear and extreme pressure properties.