UK gallons
A UK gallon is a unit of volume used in the United Kingdom for measuring liquids such as fuel and water. One UK gallon is about to 4.54609 liters or 0.16054 cubic feet making it substantially larger than the US gallon.
US oil barrels
A US oil barrel, also known as a petroleum barrel, is a volume unit used in the oil and gas industry to measure crude oil or liquid petroleum gas (LPG). One US oil barrel is 42 US gallons or about 159 liters.