Compressor lubricants have just about the toughest job of any lubricant or oil that manufacturers use. Not only do they lubricate the bearings but they seal between the rotors for efficiency and absorb the heat of compression to keep the compressor running cool. And, dependent upon the brand, they do that typically between one and three times a minute. That means that in the course of one week, a typical oil might go through one million thermal cycles of heating and cooling while ingesting dirt, getting filtered and so on. Can you think of any other lubricant that endures such punishment?