A complete theoretical study of the thermohydrodynamic characteristics of bearings lubricated with contaminated oil will be performed. Very important, yet often neglected, factors such as thermal expansion of the shaft and bearing will be considered. A mixing temperature formulation will be developed and implemented in a general finite difference computer code. Wear characteristics of the bearing and shaft will be taken into consideration. The results will be compared with those of published experimental findings. Finally, dimensionless performance parameters useful to the designers will be provided for a wide range of operating conditions as a function of particle type, size, and concentration.