Refrigerant Oil
The compressor contains a lubricant, which has greater electrical insulating properties than the A/C lubrication oil normally used for standard mechanical belt driven A/C pumps. It is important that the compressor is kept upright at all times to retain the lubricant in the compressor's sump.
CAUTION:
Use of the incorrect oil may affect the dielectric strength of the motor and potentially cause an internal short circuit as well potentially affecting the bearing life.
CAUTION:
Refrigerant oil easily absorbs water and must not be stored for long periods. Do not pour unused refrigerant oil back into the container.