HCPRO 4G refrigeration oil is a premium quality lubricant made from specially refined naphthenic base oil that is highly refined to provide the low pour point necessary for proper lubrication in refrigeration and air conditioning systems. HCPRO refrigeration oil offers excellent chemical stability when in the presence of refrigerant and other compressor materials and helps provide maximum wear protection for air conditioning compressors and components. HCPRO 4GS refrigeration oil has excellent thermal stability to ensure peak performance at high temperatures as well as excellent low temperature properties to prevent congealing in the evaporator. The oil is also wax-free to prevent floc problems in the evaporator and expansion valve.