Skip to Content

How Much Does A Gallon Of Engine Oil Weigh?(Answered)

Engine oils and fuel oils are a regular item for vehicle owners. Most owners and dealers of vehicles are well aware of the different mechanism and needs of the vehicle.

But determining the weight of the engine oil might not be an easy task. The numbers are not what they seem. You will have to do some studying to full understand the measurement scale of the engine oil.

How Much Does A Gallon Of Engine Oil Weigh?

You can weigh the measurement of a gallon of Engine oil on many scales. The most common scale is in pounds, in which a gallon of engine oil stands around 7.61 Pounds. The weigh can change according to the type as well. The Imperial gallon is roughly 7 pounds. A gallon is around 3 liters as well.

There are many types of oils used for vehicles and motors. The scale of measurement is very important as the meaning of the measurements vary according to the type of oil being used. Though people dealing with the oil and vehicle know it very well, the general people don’t.

There are different measurements to scale a gallon of engine oil. There are various types of motor oils that vary in weights as well. It is important to get the type of oil and its’ measurement right for your vehicle.

15w40 motor oil:

The average weight of a 15w40 motor oil depends on the temperature of the oil. At 32 degrees Fahrenheit the oil weighs 7.4 pounds per gallon.

And at 212 degrees Fahrenheit the weight of the oil drops to 6.7 pounds per gallon. But the average weight of the 15w40 oil is roughly 7.4 pounds at an average temperature.

30 weight motor oil:

One of the simplest measurements is the 30 weigh motor oil. It amounts to a round figure of 10 pounds. It is a more thicker type of oil and tends to weigh more than the average oils. This type of oil does not depend on the temperature, but it relies on the thickness.


This category of oil weights around 8 lbs, which is around the weight of the average engine oil. This type of motor oil is fairly common and most vehicles select this scale as it is easier to measure. 8 pounds is a standard for such motor oil.

Motor oils and engine oils have various scales of measurements. It may seem confusing to the people who do not deal with the measurements on a regular basis. However it is important for everyone to know the common measurements for the maintenance of their vehicle.

Does a gallon of water weigh the same as a gallon of engine oil?

Water is heavier than oil, which is why oil floats on top of water. The two does not weight the same. Water is always heavier than oil, even though oil seems thicker than water. There is a significant difference between the weight of a gallon f water and a gallon of oil.

Oil floats on top water because it is less heavier than water. A gallon of water can weight around 10 lbs. whereas a gallon of oil will only weight around 8 lbs. at best. This is because a gallon of water is heavier than the same scale of oil.

Water is heavier than oil and a gallon of water weights around 10 lbs. more than a gallon of oil. Where a gallon of oil weights roughly around 7.4 to 8 lbs. a gallon of water rounds at 10 lbs. The two are not the same when it comes to measurement.

How much does a gallon of heating oil weigh?

The weight of a gallon of oil depends on a lot of external factors. The type of oil or the temperature of oil matters a lot. As for the standard weight of a gallon oh heating oil, it is around 8.2 pounds per US gallons.

The heating fuel is not as dense as the other types of oil. The heating oil has a density of around 0.8. Which is why the oil is a bit heavier than the other types of oils. The weight does change according to the density of the oil. But on an average the weight stays between 8 lbs.

Fuel oil or heating oil are dense and have very specific gravity. Which is why the oil is a bit heavier, around 8 lbs. per US gallon. Heating oil are petroleum products which is why it is natural for these oils to be heavier than the other types.

What do motor oil weights mean?

One of the most confusing things about oils can be to figure out what the numbers mean. The numbers on the oil does not refer to their actual weight on the tip scale.

On top of that the numbers are written in different forms as well. This may cause a headache for new vehicle owners.

But it is not that difficult to understand once you know what each symbol and number means. You just need a good guide. And we are here to help you with that. If you feel confused just take a look at the explanation given below-

Viscosity of an oil:

The numbers represent the viscosity of the oil, which means how well the oil will flow in a specific temperature. The numbers represent thickness. So the higher the number the more thick the oil will be. Which means the flow of the oil will be slower.

Winter time number:

Most of the bottles have two numbers written on them. The two numbers are divided by a “W”. This “W” means winter and indicates the different flow of the oil during winter times.

Oils that have this type of numbering written on them are called multi grade oils. They are very unique in a way that these oils have two weights.

If you are clear about the numbers on the oil bottles then you will not face much trouble while choosing the type and weight of the fuel oil for your vehicle. The numbers are a bit confusing so be careful.

Does thicker engine oil weighs more?

The thicker the oil, the more heavy it is in weight. The weight of any type of motor or fuel oil depends on the density and thickness of the oil. So if you see an oil which is labeled at a higher weight chances are it is heavier than the average oil.

If you want a thin density oil you should go for oils that have lower numbers written on them. The numbers indicate how heavy the oil will be.

So the higher the number, the more the oil weights on the measurement scale. The numbers also indicate the viscosity, as in how the oil will flow.

The thickness of the oil determines and effects the weight of the oil. If the oil is thick then the weight will be higher or the oil will be heavier. This thickness of the oil also determines the flow of the oil in different temperature.

How to determine the weight of 1-gallon engine oil?

Determining and interpreting the weight of a gallon of engine oil may sound easy and simple. However, it is not the case.

The numbers on the engine oil bottle are very confusing and if you have no experience of reading the numbers before, there is a good chance that you will mess it up.

It is important to know how to weight a gallon of engine oil if you have an active vehicle. The thickness and the flow of the oil depends on the numbers written. You should know the meaning and the weighing system of the engine oils beforehand-

Check the weight mentioned on the bottle:

Check the number written on the bottle of the oil. There should be a number or two numbers written. If there are two numbers then they should be divided by a “W”. This means the viscosity of the oil will change to that number during winter temperature.

Know the gravity value:

You need to know the specific gravity of the oil to calculate the weight of the oil in pounds.

Check the base temperature:

Use base temperature as 60°F (15.6°C) for the measurement.

Find the API gravity value:

To find the API gravity, divide 141.5 by the specific gravity of the oil and then subtract 131.5.

The steps to determine the weight of a gallon of engine oil is not easy at all. Which is why you must be very careful with the calculation and measurements. Try to follow the steps properly and precisely to avoid making an mistakes with the calculation as it might change the results.

Final thoughts

A gallon of engine oil can be around 7.61 pounds in the US standard. And for the imperial gallon, the weight is roughly around 7 pounds. There are many scales of measurement to use for the weights of engine oil as well. You can choose whichever you feel convenient with.