Experimental results using a disc machine are given which clearly demonstrate the increase in frictional traction with time until a steady-state value less than that of the carrier oil is achieved. This increasing traction is associated with the mechanical degradation of the grease structure, which also results in a reduced film thickness. It is also shown that greases can lead to starvation, and hence failure, at higher slip speeds, and this effect is probably associated with the viscoelastic properties of the grease.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973