Is transformer oil safe for medical or body pain use?

No. Transformer oils are industrial chemicals not intended for topical or medical use. They can irritate skin, contain additives, and may include contaminants from service exposure such as degraded byproducts or other hazardous compounds. In extreme cases, legacy oils may be PCB contaminated, which is a serious health hazard. Even “non toxic” labels in an industrial context do not make them safe for human application. For body pain, use medically approved products and consult a clinician if pain persists, rather than applying industrial oils.