The hypothesis that scuffing of surfaces lubricated by a plain mineral oil results from desorption is tested for high speed cases using two types of apparatus. One uses a medium speed, 1-inch steel ball, 4-ball machine, and a simulated oil consisting of hexadecanoic acid in hexadecane. This lubricant is shown to behave in the same fashion at medium speeds as it does at very slow speeds. Thus, a graph of logarithmic concentration of acid against reciprocal absolute scuffing temperature gives a good straight line, just as at slow speeds. In the second high speed gear tester, the rise in scuff load of gears at very high speeds, the Borsoff effect, can be explained semiquantitatively by considering the residence time of molecules. These two types of results suggest that the desorption-failure mechanism may be valid over the whole rubbing speed range, and not merely at the very low speeds normally tested.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973