What is an engine oil: Different types of motor oil and grades



Engine oil or motor oil is a mixture of base oil and some kind of additives, which is used as a lubricant.

Important's of engine oil in vehicles 

Engine oil plays an important role in the life and performance of an automotive engine. Failure to take adequate care can significantly affect the performance of the engine, and even cause to cease of the piston.

Generally, the engine oil has mainly three functions

  • Lubrication
  • Remove the dust and rust 
  • Cools the engine 


Lubrication

This is the primary function of engine oil. In an engine, we can see a lot of friction zones, for example

  • Between piston and cylinder walls
  • In valve actuating mechanisms
  • Between connecting rod and crankshaft etc
Engine oil creates a thin lubricating layer between the moving parts, which resists the wear and tear of the metal parts due to the friction.


Remove dust and rust

This is another function of engine oil. The oil collects the dust and rust particles from various areas of the engine and then deposits them into the oil sump.

The deposited dust particles then drained out at the time of oil change.


Cools the engine

Another secondary function of motor oil is to cool the engine. The engine gets overheated due to the friction, and the oil absorbs some amount of heat. It will prevent the engine from overheating to some extent.


Types of motor oil (Engine oil)

Generally, the engine oil is made up of base oil and some kind of additives. The added additives help to improve the life and performance of the oil.

Anti-wear additives, anti-oxidants, viscosity index improvers, dispersants, and detergents, these are the additives used in engine oil.

There are three types of engine oils are available in the market today.

  • Natural oil (Mineral oil)
  • Semi-Synthetic oil
  • Fully-Synthetic oil


Natural oil (mineral oil)

The majority of this oil is made with base oil. The production cost is very low when compared to the other types. Which is highlighted in its life, performance, and price.


Semi-synthetic oil

This is a blend of mineral and synthetic oil.
Approximately 70% of this is normal oil and the remaining 30% is synthetic. It gives better performance at a low price.


Fully synthetic oil

The fully synthetic oil is designed for high-performance engines. This is formed after several types of quality checks. It is more costly than the other two types due to its high production cost.


Engine oil grades

The society of automotive engineers (SAE) developed a scale for identifying the engine oil grades, which is also applicable for gear oils.

Generally, the engine oil grades are calculated according to their viscosity. The higher viscosity level oils are listed in high grades and the lower viscosity levels in lower grades.

Mainly there are two types of oil grades available,

  • Monograde oil
  • Multigrade oil
In monograde oils, we can see only a single viscosity level for both the cold and hot conditions.
Eg: SAE 30, SAE 40, SAE 50, etc

Because of its single grade, the monograde oils are not used in the latest automobile engines.

In multigrade oils, we can see two viscosity levels. One for cold and the second for hot conditions.
Eg: SAE 0W30, 10W30, 5W30 etc.

W stands for winter

The number before W shows the viscosity in cold conditions (about 0-degree Celsius).

The number after W shows the viscosity in higher temperature ranges (100-degree Celsius).

An additive called viscosity index improver is added to the multigrade oils, that's why it gets two grades.

The viscosity index improver helps to maintain the engine oil viscosity to an optimum level throughout the varying engine temperatures.

Normally, the viscosity of a fluid changes according to temperature variation. At lower temperatures, it shows its high viscosity level, but an increase in temperature decreases its viscosity level.

The viscosity index improver helps to maintain a low viscosity level in low temperatures and high viscosity level in high temperatures. That's why the multigrade oil shows two grades.

An automotive engine, in cold conditions, requires a lower viscosity fluid for proper flow of fluid. In hot conditions, it is necessary to use the high viscosity level fluid to maintain the same flow. So the latest automobile engines use multigrade oils for lubrication.


2-T and 4-T oil

The 2-T oil is designed to lubricate 2-stroke engines. In a 2 stroke engine, the oil mix up with the fuel and allow it to burn inside the combustion chamber. The end products after the ignition are getting out through the exhaust port.

Whereas the 4-T oil is designed to lubricate 4-stroke engines. If a 4-T oil is used in a 2-stroke engine, which will lead to, damage to the spark plugs, blocking the exhaust port, excessive smoke emissions, etc.
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