What is the typical weight of transformer oil per litre?

Mineral transformer oil density is commonly around 0.86 to 0.90 kg per litre at about 15�C, so one litre typically weighs roughly 0.86 to 0.90 kg. Exact weight depends on oil type (naphthenic vs paraffinic), additives, and temperature. Density drops as temperature rises, so a litre at operating temperature weighs slightly less than at room temperature. Always use the supplier data sheet for logistics and mass balance calculations.