this invention describes a new refrigerant / lubricant combination for use in stationary and mobile refrigeration and air conditioning applications . in these applications , the refrigerant and lubricant must be soluble in each other to ensure adequate lubricant circulation from the compressor , through the condenser , expansion device , and evaporator , and back to the compressor . insufficient lubricant circulation will result in compressor failure . low temperature solubility is particularly important to ensure lubricant flow through the cold evaporator . in addition , the lubricant and refrigerant combination should be stable in the presence of steel , and aluminum and copper containing metals . this invention describes the combination of refrigerant difluoroethane and polar , oxygenated lubricants , particular polyalkylene glycols and polyolesters which may be used as a replacement for r - 134 a .