Phillips 66 Transformer Oil is a high quality oil that is fully inhibited for corrosion resistance in transformers and other oil filled electrical equipment. It is formulated with wax-free naphthenic base oil due to its outstanding dielectric strength. Phillips 66 Transformer Oil is designed to meet the operating requirements of ASTM D 3487 Type II fluid, providing good performance in transformers, circuit breakers, switches, and capacitors.