The data base for this study consists of the 448 life tests performed at the authors' laboratories during the four phases of an experimental program on chemical effects in contact fatigue sponsored by the Research Committee on Lubrication of ASME. Three papers have been published on the results obtained through Phase III. This paper presents statistical analyses of the combined tests and selected subsets of special interest. Eleven performance equations are given, with contact fatigue life as the measure of performance and with a number of material, lubricant, and operating factors (type of steel, surface finish, base oil, additive, moisture, slip, speed, stress, several covariates) as predictive variables. Log-normal and Weibull equations for fatigue life are compared.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Kansas City, Missouri, October 3–5, 1977