Lubrication is essential in maintaining a flowing and steady motor function. Motors are designed with the fact that lubrication will be applied to them, and a lack of it when operating can cause significant damage to moving parts.
Grease is frequently used as an electric motor bearing lubricant due to its ease of application and unique characteristics. Grease lubrication will reduce friction and prevent wear, protect bearings against corrosion and also act as a seal to prevent entry of contaminants.
With some exceptions, greases with different types of thickeners should be considered incompatible with each other. If incompatible greases are used then the grease will soften or become fluid when the motor is running.
If mixing different greases is unavoidable then make sure to test the greases when used in a mixture.
Electric motors that use double shielded or double sealed bearings do not require degreasing. All others, being open shielded or sealed bearings, should be re-lubricated periodically to replace grease that will deteriorate as the motor is used.