EFFECTS OF ORGANIC MOLYBDENUM COMPOUNDS ON THE FRICTION AND WEAR OBSERVED WITH ZDP-CONTAINING LUBRICANT BLENDS

Combining an organic molybdenum compound with a zinc dialkyl dithiophosphate (ZDP) antiwear additive can significantly reduce kinetic friction at loads in the antiwear regime as determined in laboratory, 4-ball wear tests. Both molybdenum dithiophosphates and dithiocarbamates are effective. The friction and wear benefits are independent of the ZDP present. Adding a high total base number (TBN) metallic detergent can greatly enhance the high load antixuear behavior of the three component blend xuhereas lower TBN detergents do not. Unfortunately, ashless dispersants can destroy the observed benefits. The performance improvements obtained with organic additives could not be duplicated by adding specific inorganic solids, either singly or in combination. © 1990 Taylor & Francis Ltd.