Grease of good quality and correct quantity is used as the lubricant in the bearings. The normal regreasing interval is around 4000 hrs. (around 6 months). When greasing is required, ensure that the same grade of grease is used. Any Lithium based equivalent grease can be used, but should be carefully checked to avoid mixing of dissimilar makes of greases. Care should be taken not to grease frequently or too liberally as this can lead to overheated bearings. The original grease should not be removed unless it has become dirty, deteriorated or caked. When the machine has to be stationary for a long period of time, the rotor should be turned periodically, to avoid settling of the grease at the bottom of the housing.

In all the generators (both single and double bearing) the bearings used at the nondrive end are of sealed type lubricated for lifetime and hence no regreasing is necessary.