Air compressor oil is standard or synthetic oil made specifically for air compressors. Unlike motor oil, air compressor oil does not contain detergent and typically has lower amounts of carbon, sulfur, an.
[pdf] The solution here is to check and clean the unidirectional valve, replacing it when necessary. Improper installation or blockage of the oil return pipeline will impede the normal return of the lubricating oil.
[pdf] If the capacity of the air compressor is really too low, check the following: Check differential pressure over oil separator. Replace separator when necessary. Check and replace compressed air filters (if installed). Compressor does not unload. Check if pressure switch is correctly set and working.
[pdf] 
