Shell Refrigeration Oil S2 FR-A is a low miscibility compressor lubricant intended for use in refrigeration compressors using Ammonia refrigerant. It is formulated from specially refined paraffin base oils in combination with additives selected to minimise system deposits and provide long service life. System efficiency. Shell Refrigeration Oil S2 FR-A has been specially optimised for use in systems where oil separation is required. It has been designed to reduce light end oil carry over; this minimises oil thickening in the compressor and reduces oil coating of internal evaporator surfaces thus maintaining overall system efficiency. Extended maintenance intervals. Shell Refrigeration Oil S2 FR-A has excellent high temperature and oxidation stability providing long service life even where high compressor discharge temperatures are found. In addition it is formulated to provide excellent control of deposit and sludge formation resulting in extended oil drain intervals in comparison with conventional mineral oil based refrigerator oils. Refrigerator compressors. Shell Refrigeration Oil S2 FR-A is recommended for. use in open- semi-open and hermetic compressors. in domestic commercial and industrial refrigeration. systems. It can be used in both rotary and reciprocating compressor types. Refrigerant compatibility. Shell Refrigeration Oil S2 FR-A is recommended for use with ammonia (R717) based refrigeration systems where it offers excellent performance even under high compressor discharge temperatures or down to evaporation temperatures of -30C.