Castrol Aircol 228 range of refrigeration oils are formulated from selected alkyl-benzene base stocks. Suitable for use in R22 refrigeration systems with very low evaporator temperatures where Alkyl-benzene based lubricants are recommended by the manufacturer. These products may not be suitable for use in refrigeration systems employing screw compressors due to the high level of solubility of refrigerant in the lubricant, which may reduce its viscosity to unacceptable levels. However this is largely dependent on operating conditions.