Wear and friction properties of three representative neopentyl polyol esters, together with the common diester lubricant base, bis(2-ethylhexyl) sebacate, were studied with the four-ball wear machine at 266 F and 5–50 kg load in the presence and in the absence if tricresyl phosphate. The rubbing surfaces were 52100 steel, 440 C stainless steel and M-50 steel. With 52100 low-chromium steel balls, wear rates were largely independent of ester type. Percolated tricresyl phosphate reduced wear moderately at low loads only. Stainless steel 440 C and M-50 steel gave results significantly different from those with 52100 steel at all loads. In the case of the stainless steel wear was greatly increased at a load of 50 kg and tricresyl phosphate (1%) was ineffective at all loads. M-50 steel gave the lowest wear rates. It showed no response to tricresyl phosphate. Average friction coefficients of all the steels showed little change with the variables examined except for a small increase with load and for slightly lower values with M-50 steel.Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.