Leading Indian manufacturers commonly cited in industry include APAR Industries, Savita Oil Technologies, and Gandhar Oil, among others, producing mineral insulating oils and related grades for transformer applications. APAR markets itself as a major global supplier of transformer and specialty oils, while Savita publishes dedicated transformer oil product information, and Gandhar offers transformer oil grades under its portfolio. For procurement, utilities typically shortlist based on IEC 60296 alignment, consistent batch testing, and supply capability, rather than brand name alone.