TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The second refrigerant or replacement refrigerant composition (C1) comprises the synthetic lubricant component (1-25 wt.%, of the total amount of lubricant in the system). The lubricant composition (C1a) comprises the synthetic lubricant component (1-25, preferably 1-20) wt.%. Preferred Components: In the method (M1), the first lubricant is a hydrocarbon-based lubricant. In the method (M1) and in the composition (C1a), the hydrocarbon-based lubricant comprises mineral oil.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: In the second refrigerant or replacement refrigerant (C1) and the composition (C1a), the lubricant comprises polyol ester (POE) as the synthetic lubricant. EXAMPLE - Kauri-butanol value measurement for mixtures of refrigerant, mineral Oil, and polyol ester (POE) lubricants, was carried out as follows. The measuring of KB value for refrigerant/lubricant mixtures was adapted from ASTM D1 133-09 for use on mixtures of gases and liquids. A Kauri-butanol (KB) solution (20 g) was added to a sealed aerosol bottle. A mineral oil-POE mixture was added to a second sealed aerosol bottle. A refrigerant was then added to the second aerosol bottle under pressure until layer separation of the materials occurred. This second bottle containing the mineral oil-POE-refrigerant mixture was inverted so that the oil mixture saturated with the refrigerant was at the bottom with a small dip tube and the remaining immiscible refrigerant (both liquid and vapor) were on the top. The oil layer under pressure was then slowly added to the KB solution aerosol bottle via a transfer tube between the bottles. The KB solution bottle was swirled as the oil mixture saturated with refrigerant was added and addition continued until a defined degree of turbidity was reached. The weight of oil mixture transferred was recorded and KB value was calculated as per standard calculation described in the ASTM method. The results were obtained for the refrigerants R407C (a mixture of 23 wt.% difluoromethane (HFC-32), 25 wt.% 1,1,1,2,2-pentafluoro-ethane (HFC-125), and 52 wt.% 1,1,1,2-tetrafluoroethane (HFC-134a)); and R438A (a mixture of 8.5 wt.% HFC-32, 45 wt.% HFC-125, 44.2 wt.% HFC-134a, 1.7 wt.% n-butane, and 0.6 wt.% isopentane). The test compositions containing (wt.%): R407C (50), and Suniso 3GS (RTM: naphthenic mineral oil) (50); R407C (50), Suniso 3GS (37.5), and Emkarate RL32H (RTM: polyol ester) (12.5); R407C (50), Suniso 3GS (25), and Emkarate RL32H (25); R438A (50), and Suniso 3GS (50); R438A (50), Suniso 3GS (37.5), and Emkarate RL32H (12.5); and R438A (50), Suniso 3GS (25), and Emkarate RL32H (25); showed KB values of 27.8, 34.3, 40.9, 28, 35.3, and 38.8, respectively. The control compositions containing (wt.%): R407C (100) and R438A (100); showed KB values of 11.2, and 12.2, respectively. The results showed that even in the presence of refrigerant with the lubricant, mixtures with lower amounts of POE still had lower KB values. Adding lower amounts of POE could aid oil return, while reducing the potential to dissolve and redeposit contaminants in the system which can result in system performance issues.