FJC 2432 Estercool Advanced Refrigerant Oil (Quart) The most technologically advanced R134a and R12 oil on the market today Compatible with Mineral, Ester, Paraffin and PAG Oil Add to any existing R12 or R134a mobile a/c system All natural Ester oil that contains additives that lubricate and protect the system Prevents acid from forming and inhibits corrosion