What is the chemical classification of transformer oil?

Transformer oil is typically a refined petroleum derived mineral oil, chemically composed mainly of hydrocarbons such as paraffinic and naphthenic components with small aromatic content depending on formulation. It may contain additives such as oxidation inhibitors in inhibited oils. Alternative transformer fluids include natural esters, synthetic esters, and silicone fluids, which have different chemical classifications and environmental profiles. Classification in SDS documents covers hazards, handling, and regulatory status, including whether the oil is non PCB and its transport classification.