Synthetic lubricants comprising 15 to 45 weight percent of an ester of a monohydric alcohol of 4 to 18 carbon atoms with one or more aromatic or alkane dicarboxylic acids having 4 to 18 carbon atoms blended with 85 to 55 weight percent of one or more polyether polyols having a number average molecular weight from about 400 to 5000. The blends are compounded with antioxidants, corrosion inhibitors, and metal deactivators to produce a superior lubricant for reciprocating air compressors which gives a long life to the compressors.