What is the typical weight per gallon of transformer mineral oil?

Mineral transformer oil density is commonly around 0.86 to 0.90 kg/L at room temperature, varying by formulation and temperature. One US gallon is 3.785 L, so a practical weight range is roughly 3.3 to 3.4 kg per gallon, or about 7.3 to 7.5 lb per gallon. For transport planning, temperature correction matters because oil expands and density drops as temperature rises.