The performance of friction material in an oil-cooled environment is greatly influenced by conditions of use. Power, speed, oil flow, and inertia are some of the factors whose effects on material performance have been documented in the literature. These factors interact in a complex manner which makes it difficult to predict material performance.The effects of several major factors-power, speed, inertia, oil flow, and reaction plate thickness-were investigated using an inertia dynamometer.The program was designed to assess the relative significance of each factor in determining material performance and to examine how effects of each factor are modified by interaction with other factors. Three materials were tested. Groove pattern was investigated as a means of modifying the effects of other factors.