Lubricant selection is of critical importance for the performance of a ball bearing. It affects Life, Torque, Speed, Noise, Grease migration, Outgassing, Temperature effects and rust prevention. In most cases XW supplies ball bearings as a complete unit, pre-lubricated with grease. It is not normal to re-lubricate ball bearings as they are "sealed for life".
There are literally hundreds of lubricants available for ball bearings; selecting the optimal one is critical. Each has a particular characteristic which makes it suitable for a specific application. Unless torque is a problem, grease is preferred for prepublication since it is less susceptible to migration and leakage. Grease can increase bearing torque by a factor of 1.2 to 5.0 depending on the grease type and quantity used.