A refrigerant system comprising: a compressor having a flow of compressor lubricant therein, the compressor compressing a flow of vapor refrigerant therethrough; an evaporator operably connected to the compressor including an environment to be cooled via a thermal energy exchange with a liquid refrigerant in the evaporator; and a lubricant recovery system including: a vaporizer receptive of a first flow of compressor lubricant and refrigerant mixture from the evaporator having a first concentration of lubricant, the vaporizer using a flow of compressed refrigerant to boil off refrigerant from the compressor lubricant and refrigerant mixture; and a lubricant sump receptive of a second flow of compressor lubricant and refrigerant mixture from the vaporizer having a second concentration of lubricant greater than the first concentration; characterized by : a heat exchanger receptive of a third flow of compressor lubricant and refrigerant mixture from the lubricant sump having a third concentration of lubricant, the heat exchanger using evaporator suction gas to cool the third flow of compressor lubricant and refrigerant mixture, thereby increasing its viscosity before urging the third flow to the compressor to lubricate the compressor; and a compressor heat exchanger using compressor discharge gas to heat lubricant flowed from the compressor to the lubricant sump . a compressor having a flow of compressor lubricant therein, the compressor compressing a flow of vapor refrigerant therethrough; an evaporator operably connected to the compressor including an environment to be cooled via a thermal energy exchange with a liquid refrigerant in the evaporator; and a lubricant recovery system including: a vaporizer receptive of a first flow of compressor lubricant and refrigerant mixture from the evaporator having a first concentration of lubricant, the vaporizer using a flow of compressed refrigerant to boil off refrigerant from the compressor lubricant and refrigerant mixture; and a lubricant sump receptive of a second flow of compressor lubricant and refrigerant mixture from the vaporizer having a second concentration of lubricant greater than the first concentration; a vaporizer receptive of a first flow of compressor lubricant and refrigerant mixture from the evaporator having a first concentration of lubricant, the vaporizer using a flow of compressed refrigerant to boil off refrigerant from the compressor lubricant and refrigerant mixture; and a lubricant sump receptive of a second flow of compressor lubricant and refrigerant mixture from the vaporizer having a second concentration of lubricant greater than the first concentration; characterized by : a heat exchanger receptive of a third flow of compressor lubricant and refrigerant mixture from the lubricant sump having a third concentration of lubricant, the heat exchanger using evaporator suction gas to cool the third flow of compressor lubricant and refrigerant mixture, thereby increasing its viscosity before urging the third flow to the compressor to lubricate the compressor; and a compressor heat exchanger using compressor discharge gas to heat lubricant flowed from the compressor to the lubricant sump . a heat exchanger receptive of a third flow of compressor lubricant and refrigerant mixture from the lubricant sump having a third concentration of lubricant, the heat exchanger using evaporator suction gas to cool the third flow of compressor lubricant and refrigerant mixture, thereby increasing its viscosity before urging the third flow to the compressor to lubricate the compressor; and a compressor heat exchanger using compressor discharge gas to heat lubricant flowed from the compressor to the lubricant sump . <EOS>