Wikipedia
Polyolester oil (POE oil) is a type of synthetic oil used in refrigeration compressors that is compatible with the refrigerants R-134a, R-410A and R-12. It is recommended by experts as a replacement for hydrofluorocarbons (HFCs). Along with R-134a mineral oil it is recommended as a replacement for R12 mineral oil as R134a does not mix well with mineral oil. These wax-free oils are suggested for use with chlorine free HFC systems as they provide better lubrication and stability and are more miscible with HFC refrigerants. They can meet the lubricity requirements to those of mineral oils used with CFCs and HFCs. They are compatible with most lubricants in the market. It is noted that the viscosity of the oil increases with temperature. The dispersion behavior of this oil has also been the subject of a lot of study. It is also considered by some to be a good additive to engine oil.