Abstract: A high quality lubricant for hermetically sealed domestic air conditioner and refrigerator compressors, especially those using chlorine free hydrofluorocarbon refrigerant working fluids, is provided by mixed esters of hindered polyols, most desirably pentaerythritol, with a mixture of carboxylic acids including at least some isopentanoic acid along with either or both of iso-nonanoic acid and dibasic acids such as adipic.

Abstract: A two-step process comprising as a first step draining a refrigerant heat transfer fluid made of molecules containing at least one chlorine atom per molecule and mineral oil lubricant dissolved therein from an unflushable compressor and associated piping in a vehicle air conditioner, thereby leaving a mineral oil residue. The second step comprises replacing the refrigerant heat transfer fluid in all parts of the vehicle air conditioner designed to contain such fluid with a replacement heat transfer fluid. The replacement fluid consists essentially of 1,1,1,2-tetrafluorethane and a composition of matter suitable for serving as the lubricant or lubricant base stock. The composition of matter is capable of forming a soluble clear solution with a mineral oil residue in a weight ratio of mineral oil to composition of at least 25:100 and forming a single phase with 1,1,1,2-tetrafluoroethane between −55° C. and +71° C.