What are the list of transformer oil manufacturers in India?

The list of transformer oil manufacturers in India includes several prominent companies. Key manufacturers are Indian Oil Corporation Limited (IOCL), Bharat Petroleum Corporation Limited (BPCL), Hindustan Petroleum Corporation Limited (HPCL), and Reliance Industries Limited. Additionally, companies like Castrol India Limited and Apar Industries also produce transformer oil. These manufacturers provide a range of transformer oils that meet industry standards for power transformers.