| abstract |
The performance of lubricants having a mineral oil or synthetic oil base can be improved greatly by dithiophosphates of zinc, lead, tin, tungsten, molybdenum, niobium, lanthanum, antimony, bismuth, chromium, vanadium, or cadmium esterified with alkyl, aryl, or alkyl-aryl groups in synergistic cooperation with additives free from heavy metals, but containing sulfur and phosphorus, such as sulfides of phosphorus and known addition agents. |