What type of lubricating oil is primarily used with R-22 air conditioning compressors?

Mineral oil is primarily used with R-22 air conditioning compressors because R-22, a hydrochlorofluorocarbon (HCFC) refrigerant, was designed to work effectively with oils that are mineral-based. This type of oil, derived from refined petroleum products, has ideal properties for R-22 systems, including good solvency, compatibility with the refrigerant, and the ability to maintain stable lubrication under the temperature and pressure conditions typical in such systems.

Using mineral oil helps maintain the necessary lubrication of the compressor components, promoting efficient operation and longevity of the equipment. In contrast, other oils such as polyolesters and polyalkylene glycols are specifically formulated for use with refrigerants that require a different compatibility, such as R-134a and newer HFCs. Therefore, while these alternatives may have distinct advantages in different contexts, they do not align with the traditional requirements for R-22 systems.