Oil lubrication plays such important part in the maintenance of bearing products
, thus, the selection of it also becomes rather important. Selecting oil is primarily based on the viscosity required to provide adequate lubrication for the bearing at the bearing operating temperature. The viscosity of oil is temperature dependent, becoming lower as the temperature rises. And in order for a sufficiently thick oil film to be formed in the contact area between rolling elements and raceways, the oil must retain a minimum viscosity at the operating temperature.