Compressor oil must be compatible with both the refrigerant and the system design.
Mineral oil
It was widely used with older refrigerants and is not suitable for all modern systems.
POE
It is common in many HFC/HFO systems and is hygroscopic.
PVE
It is used in certain modern applications and has different compatibility and moisture management characteristics.
Rule
Use exclusively the type of oil specified by the manufacturer.
