A gallon of gasoline weighs 6.3 lb which is slightly less than a gallon of oil which weighs roughly 7.61 lbs.

Water is actually more heavy than oil in weight.

The density of water(1000 kg/m3) is higher than the density of oil(870 kg/m3).

Water molecules are made up of oxygen and hydrogen atoms bonded together.

Oxygen is heavier and smaller than carbon, so a volume of water molecules is heavier than the same volume of oil molecules.

This makes water more dense than oil.

Also, water molecules are very attracted to each other and pack very close together.

A gallon of oil weighs 7.61 lbs.

The weight in lbs of a gallon of oil is 7.61lbs.

A gallon of oil weighs roughly 7.61 lbs per gallon and 5 gallons of oil weighs around 38 lbs to 40 lbs.

A 55 gallon drum of oil weighs 444lbs.

A 55 gallon drum of water weighs slightly more than the 55 gallon drum of oil as the 55 gallon drum of water weighs around 484lbs.

A 42 gallon drum of oil weighs around 300 lbs.

A standard-size barrel holds 42 U.S.gallons.

If one fills a standard sized barrel with petroleum oil that has a density of 881 kg/m3, then that barrel weighs about 300 pounds.

If one fills the same barrel with crude oil with a density of 790 kg/m3, that barrel weighs about 275 pounds.

The volume of a barrel of oil is quite specific and equal to about 35 imperial gallons (42 US gallons, about 159 liters).

A barrel of oil is also significantly heavy.

Since average domestic crude oil weighs about 7.21 pounds per gallon, a barrel of oil weighs around 300 pounds or about 136 kilograms.

The density of water(1000 kg/m3) is higher than the density of oil(870 kg/m3).

According to the mathematical equation, mass =density*volume. Now keeping the same volume for both water and oil the mass would be greater for water. Hence the water is heavier than oil.