Settling the Confusion: Engine Oil Vs. Gear Oil

A lot of people are confused between engine oil and gear oil. So they ask, “Are engine oil and gear oil irreplaceable?” No, they are not. Engine oil and gear oil are two different types of lubricants and here we discuss how exactly are they different from each other.

What is engine oil?

The engine oil is a lubricant used to layer engine parts and fill the empty spaces in the engine body. Engine oils come with special additives that protect the engine against wear and tear. Engine oils are available in three basic variants- conventional oil, synthetic oil, and semi-synthetic oil.

Benefits of engine oil

Here are the best advantages of having your engine filled with high-quality engine oil:

  • Increased lubrication

The first function of the viscous, yet easily flowing engine oil is to lubricate the entire engine body and minimise friction.

  • Cleaner engine

Different basic engine oil additives like detergents and dispersants work to remove all dirt, gunk, and grime from the metal surfaces of the engine.

  • Improved fuel efficiency

A cleaner engine allows the fuel to flow better in the engine, enabling the engine to generate more power while utilising less fuel.

  • Reduced vehicular emissions

Used-up engine oil is vulnerable to burn in the engine’s combustion process, resulting in vehicular emissions. On the contrary, fresh engine oil is less likely to burn and is even able to absorb engine by-product emissions.

What is gear oil?

Gear oil is a lubricant specially designed for the transmission, differentials, and transfer cases of the engine. The gear oil is a thick fluid that comes with additives to protect the gearbox. Gear oils are also available as conventional gear oils and synthetic gear oils.

Benefits of gear oil

Here are the top reasons why you need a premium quality gear oil for your automobile:

  • Thermal stability

The engine of your car, especially the gears, have to undergo immense amounts of heat and pressure that are totally not good for the metal surface of the gearbox parts. Gear oils are designed to provide excellent performance when the load carrying capacity of the engine is required due to shock loading and extreme pressures.

  • Water separation

Moisture is detrimental for the gearbox. It not only catalyses the production of rust and corrosion, but it also increases friction while building up heat in the engine system. Gear oils come with additives that create a protective, separation film on the metal surface, thus preventing any moisture from getting in contact with the metal.

  • Clean gears and bearings

The gear oil additives also function to remove and clean gunk and grime from the metal surface. Doing so straightaway increases the efficiency and performance of the vehicle.

  • Minimized deposits

Apart from cleaning the gunk residues, the gear oil additives also aid in preventing future build-up of deposits.

  • Prevention of rust

When a combination of oxygen and moisture come in contact with the metal surface, acids are formed. These acids result in the formation of rust that eats up the metal surface. By cutting off the contact of metal and moisture, gear oils also prevent the production of rust.

Differences and similarities between engine oil and gear oil

If the definitions have still not cleared your confusion, here’s the exact comparison between the two oils:

●    Similarities

  • Engine oil and gear oil both serve as lubricants.
  • Both of them are added with special compounds to enhance their abilities.
  • The base of both the lubricants is either made of synthetic oil or mineral (conventional) oil.

●    Differences

  • Gear oil is oftenly thicker in consistency than engine oil.
  • Engine oil lubricates the entire engine body while gear oil is specifically for the gearbox.
  • Up until recently, gear oils were added with EP protection additives that were slightly acidic in nature. Acidity is never wanted in an engine oil.
  • Engine oils are a greater number of antioxidants than gear oils.


So, here were the basic similarities and differences between engine oils and gear oils. Hope this article was helpful and it made you make the right decision for your automobile. Another great decision will be to choose only premium car lubricants from a reliable car parts and accessories store online for your engine as they directly affect the longevity of the engine.