Engine Oil vs Motor Oil – Is There Any Differnce

I had to drive from Los Angeles to Dallas for Christmas. My car had run 8000 miles after the last oil change so I decided to change my engine oil before leaving. As I reached the garage, I saw a poster advertising ‘Motor oil’ which got me confused. Whether it is engine oil or motor oil? What is the difference?

Finally, I decided to ask my friend who was a chief engineer at Mobil Engine oil to explain the difference between these two terms. He gave me a sarcastic smile and replied, “the difference is the same as that between gasoline and petrol” i.e., they are one and the same thing. I was a bit startled!


Why Do We Get Confused Between ‘Engine Oil’ And ‘Motor Pil’? (Are They The Same?)

The term ‘engine oil’ is mostly used in the US whereas the term ‘motor oil’ is generally used in the UK. This might be a reason for confusion as primarily, everyone uses only one of the above terms.

Also, the term ‘motor’ is generally understood as an electric motor but the reality is that the terms ‘motor’ and ‘engine’ are virtually synonymous.


What is Engine oil or Motor oil Anyway If You Are Still Confused?

Engine oil or Motor oil is a combination of base oil (refined crude oil) and additives such as dispersants (for better spraying), detergents (for better cleaning), anti-wear additives, friction modifiers (for better lubrication), anti-foam additives, viscosity index improvers (for the suitable thickness of oil), etc.

  • The engine is made up of mechanical components which undergo a lot of friction. Engine oil acts as a lubricant that eliminates friction and prevents the components from wear and tear.
  • The operating temperature for most car engines is about 220 degrees Fahrenheit. On top of that, the friction increases the temperature further. Engine oil and engine coolant work in harmony to cool the engine.
  • The engine oil fills the small gaps in the engine components and works as a sealant so that the engine is well packaged and each component can interact with connecting components efficiently.
  • The flow of the oil through the engine components ensures that the engine remains clean and helps prevention of sludge formation.


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Which Engine Oil Should You Prefer for Your Vehicle?

I cannot stress this enough, always use the engine oil prescribed in the owner’s manual. It is the most integral part of choosing the engine oil of your car.

If you are considering the engine oil recommended by a mechanic, always remember to inform him of the type of fuel your car uses. This is because the engine oil used in a diesel engine and a petrol engine is different in nature. A diesel engine uses thicker engine oil as compared to its petrol counterpart so as to deal with a higher compression ratio. Also, the additives in a petrol engine might vary as compared to additives in a diesel engine.

For high mileage vehicles (over 75,000 miles), it is recommended to use mineral oil or high-mileage engine oil specially made for high mileage vehicles.


Types of Engine oils

  1. Mineral oil – This is the conventional engine oil that has been in use since the beginning of Internal Combustion Engines (ICE). It is obtained by refining the naturally occurring crude oil.


  • It is cheaper.
  • It is easily available.


  • It flows slowly resulting in higher fuel consumption.
  • It loses its lubricating properties and degrades quickly resulting in frequent oil changes.


  1. Synthetic oil – It is made by scientists in laboratories, so they are exemplary in almost every sense. Each molecule of synthetic oil is uniform and hence, it results in smoother flow through the engine.


  • It remains fluid even in sub-zero temperatures allowing it to be used in the colder regions.
  • It is smoother as it has less viscosity which translates to better engine and fuel efficiencies.
  • It requires lower levels of viscosity index improvers which degrade the quality of oil as the oil ages. Therefore, it lasts longer.
  • Less sludge formation which leads to a healthier engine.


  • It is costly.
  • It is not recommended for older engines.


  1. Semi-synthetic oil – It is obtained by mixing mineral oil and synthetic oil. It provides a middle ground that has the qualities of both mineral oil and synthetic oil.


  • It provides better performance and engine protection as compared to mineral oil.
  • It is cheaper than synthetic oil.


  • Its performance is not equivalent to fully synthetic oil.


Brands of engine oil

Some popular brands of engine oil are-

  • Mobil
  • Valvoline
  • Shell
  • Pennzoil

Generally speaking, brands do not make that much of a difference to the engine’s overall performance. Just check the ‘viscosity grade’ recommended in the owner’s manual and then you can choose any of these brands.

And yes, you can top up with engine oil from a different brand keeping the point mentioned above in mind.



I believe I have uncluttered your mind regarding this misinterpretation of these two common terms- ‘Engine oil’ and ‘Motor oil’. No matter what you might call it, do not forget to top up and change your engine oil as required. It matters a great deal!