Electric motors have bearings with permanent lubrication, requiring no additional lubrication.
The compressors have their own oil supply (oil recommended by the manufacturer).
For adding oil to installations with long gas lines check recommendations in the manufacturer's manual. The compressors have an oil sight glass for checking the level.
The oil level must be checked when the compressor is running in stabilized conditions. In this case, the oil level must be between 1/4 and 3/4 of the oil sight glass.
