Why Is The Density Of Engine Oil So Important?

The oil density enhances with oxidation progress. Actually, density plays a vital role in how lubricant works as well as machines work. Most systems are specially built to pump a liquid of a specific thickness.

Ergo, as the density changes, the pump efficiency also starts to change. If you don’t understand the density of engine oil, then your engine cannot correctly perform and work.

That’s why knowing the engine oil density is so important.

As you know, viscosity calculates how oil can flow easily at a specific temperature. Depending on the viscosity measurement, the internal resistance can significantly perform. Knowing about density is also essential to learn more about this topic, so keep reading.

Density of Engine Oil

What Is The Density?

Density is a primary property in all fluids, not only in lubricants. Mathematically, this measures a mass substance and its relation in a relative volume.

For example, if lubricant density increases, the fluid will be thicker. It enhances the time and takes for particles to settle out of suspension. But before discussing in detail, it’s essential to know what density is?

See: Thickest Oil

The density formula is d = M/V, which means d is density, M is mass, and v is volume.

The fluid density changes for any reason and can convert the errors of both values of consistency. Besides this, the common word for density is specific gravity in conjunction, that is, the relationship of water with density.

In other words, density defines specific gravity and relates to the oil’s viscosity. Water comes with much density from engine oil and works with a lower viscosity. According to the Association of Automotive Engineers standard, the oil viscosity is determined on the market.

Measuring Density of Lubricants:

Most of the oil density will range between 700 & 950 KGs per cubic meter. Lubricants usually refer to the temperature of +20°C or +15°C in a unit’s kg. Water comes with 1000 kg/m3. That means, on water, most of the oil will float because oils are lighter by volume.

Usually, if oil density is lower than water, it will float. That’s why; if your lube system has a moisture problem at the bottom of the sump, the water settles. This case will always not happen because some Group-IV-based lubricants will have a superior density to water. For that reason, effectively, the oil will sink into the water.

Relation of Density Temperature:

On the temperature, the density is dependent, though the dependency is nearly small compared to the viscosity of lubricants. Below is the experimental formula, and1 2, you can use it to calculate the density change with temperature:

P= PT1 + ap (T1 + T) where AP = 0.65 for 831KG/m3 < p < 950 kg/ m3 and AP = 0.6 for 950kg/m3 <= p < 1000kg/m3.

As you can see, the experimental relation is only suitable for oils with densities in a certain range. Nevertheless, these specified ranges can cover the most used (860-980) lubricating oils.

The density of engine oil:

p=0.8848 g/cm3

p=884.8 kg/m3

p=0.8848 g/ml

p=884.8 g/L

p=55.2363 lb/ft3

15W-40 Engine Oil Density:

The density of 15w-40 engine oil weighs 0.8725 gm per cubic cm or 872.5 kg per cubic meter. SAE 15W-40 engine oil density equals 872.5kg/m3; at 30°C or 303.15k at normal atmospheric pressure. In the US customary or imperial measurement system, the density = 54.4684 pounds per cubic foot.

Density Test Standard

ASTM D5002-19:

Standard Test Processes by Digital Density analyzer for density, API Gravity of crude oils, and Relative density. Yet, this test process can cover the determination of crude oil’s relative density, density, and API gravity.

Even this method will cover that it can handle fluids between 15 °C and 35 °C. Precisely, this test process suits crude oils with high vapor pressures. Generally, during the analysis of density, the analyzer takes proper precautions to prevent vapor loss.

ASTM D1298-12:

Standard Test Method is best for Relative Density, Density, or API gravity of liquid and crude petroleum tested by Hydrometer Method. Additionally, this test process can cover the determination of the laboratory by applying a glass hydrometer.

Usually, these test processes do this with a calculation of relative density, API gravity, and density. At existing temperatures, the values are assured and corrected to 60°F or 15°C by calculations and international tables.

What’s The Density Of Used Engine Oil?

After two years of using this engine oil, the lubricants of physical properties will weaken. In the same way, the colors of engine oil change from yellow to brown. Carbene derivatives, Asphaltenes are the main equipment leading to the sealing of lubricants.

SAE 15W-40 engine oil weighs 0.8725 gm per cubic cm or 872.5 km per cubic meter. Also, SAE 15W-40 density of engine oil = 872.5 kg/m3 at 30°C at normal atmospheric pressure. What’s The Density Of Engine Oil?

SAE 15W-40 engine oil weight is 0. And there are 8725 GMs per cubic meter. In many cases, engine oils have a density of 700 to 950 (kg/m3) per cubic meter. According to the definition, water comes with a 1,000 kg/m3 density. As a result, most of the oils float in water because they are very light by volume.

engine oil density


Q. What is the average density of oil?

you can find the density of oil by using the formula, which is already discussed earlier. Generally, most engine oil density kg/m3 is between 700-900. For Example, the density of 10W30 engine oil density is 865 Kg/m3.

Q. Which has higher density water or oil?

Oil density is higher than water and that’s why oil floats on the water. Oil density kg/m3 is between 700-950 whereas water density is almost near about 1000 kg/m3.

Final Word:

Above all, the physical volume and mass rate determine engine oil density. Along with consistency, the parameter comes with direct dependence on temperature. During hydraulic transmission, this engine oil density provides power.

On the contrary, low-quality motor oil includes dangerous additives and used motor oil contains impurities that can enhance density parameters. To conclude, this is the article where you can find complete information about the density of engine oil and why it’s so important.

Read Also :

Viscosity of Oil

Flash Point Of Motor Oil

What Is TBN In Engine Oil?


Emon is Lubricants specialist who studied on Petroleum Engineering in UAE. He have more than 10 years experience on different kinds of lubrication including automobile troubleshooting.