Sinopec Insulated Transformer Oil is a series of products blended using highly refined mineral oil and a selected antioxidant. It is designed for insulating and cooling transformers, oil-immersed switch-gear and other electrical insulating applications. There are four grades, I-0℃, I-10℃, I-30℃ and I-40℃, which are selected on the basis of their low-temperature performance. None of the grades contain harmful polychlorinated biphenyls (PCBs).