its a Campbell Hausfeld compressor, the mono grade gets to thick in the winter and it won't turn the compressor. The manual says nothing about using compressor oil. http://www.chpower.com/chpdfs/manual04/615600_0605.pdf
1. Allow compressor to run and warm
up oil. Unplug unit.
2. Position a pan under pump end of
3. Remove oil drain plug (see Figure 6).
Allow oil to collect in pan. Tilt unit to
4. Replace drain plug, fill pump to full
line on sight glass. Use Chevron
synthetic 5W-30, Mobil 1 5W-30 or
10W-30 synthetic motor oil. Using
other types of oil will cause starting
5. Change oil after every 50 hours of