a 55 Gallon Drum of Oil — the weight
Short answer: about 396 lb of liquid (180 kg). The longer answer below includes the container, the handling math, and the mistakes to avoid.
Petroleum products are lighter than water, so an oil drum is friendlier than a water drum: 55 gallons of lube or heating oil at ~7.2 lb/gal is ~396 lb of liquid, ~440–450 lb gross in a steel drum. Diesel (~7.05) and hydraulic oil (~7.0–7.4) land within a few pounds of the same.
The number that matters for buying and selling: a drum of oil is also commonly traded by weight — 396 lb is almost exactly 180 kg, and many specs quote "180 kg drum" for this reason.
Same handling rules as the water drum apply, with one addition: oil drums get pumped or tilted with a drum cradle, never poured, and a partial drum's weight is exactly what the drum chart inches say times 7.2.
FAQ
How much does a 55 Gallon Drum of Oil Weigh?
About 396 lb of liquid (180 kg) at 7.2 lb/gal, plus the container's tare weight — details above.
Where do these densities come from?
From the cited reference values on our weight library and methodology pages, each with grade ranges and temperature basis stated.