The lubricant film thickness of grease-lubricated, cylindrical roller thrust bearings was measured, using a capacitance type displacement probe. For comparison, the same tests were also performed with the bearings lubricated with mineral oils. The film thickness and friction torque as a function of rotational speed were determined both under fully flooded and starved lubrication conditions. The test results show that the lubricant film thickness in grease-lubricated bearings is influenced by the base oil, and the thickener.Presented as an American Society of Lubrication Engineers paper at the ASLEIASME Lubrication Conference in Minneapolis, Minnesota, October 24–26, 1978