A barrel of oil (assuming that's what you mean by a drum) is 42 US gallons, (160 liters) That is not all gasoline of course, there are other fractions like kerosene, diesel, and heavy fuel oil to...
An empty oil drum usually weighs 100lb-500lb.
You are looking at up to 500 lbs if it is full......
1 barrel of oil = 158.987295 liters1 barrel of oil = 42 US gallons
It depens on the size of the oil cooler.