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Rolling contact fatigue is a particular type of fatigue that occurs in heavily loaded, non-conformal contacts, such as gears and rolling element bearings. It is primarily a failure mode associated with repeated cyclic loading that generates high local Hertzian pressures, leading to local plastic deformation and substantial surface or sub surface stress. This in turn leads to crack formation and propagation. In some instances this results in sudden and often critical mechanical failure of contacting parts. This failure mode can, to a certain degree, be controlled by the appropriate choice of lubricant; in terms of both the physical and chemical properties of the films formed at the surface. A three contact disc machine has been used to examine the rolling contact fatigue of motorcycle lubricants in such heavily loaded contacts. Three counterface test rings of equal diameter (54mm) are mounted 120° apart with a smaller (12mm diameter) test roller in the centre.