What is the Function of Lubricating Oil?

The function of Lubricating oil means why the oil is used in the engine. In this article, I will discuss the function of lubricating oil in an engine.

Function of lubrication oil.

The function of Lubricating Oil

There is always friction between two surfaces when they rub against each other no matter how highly polished surfaces are, such as the shaft in a bearing, or the piston in a cylinder.
Irregularities of the highly polished surface can be examined under a magnifying glass or microscope. The high points of one irregular surface strike the high points of another irregular surface when they are rubbed with each other. 
Without lubrication between two surfaces, the heat generated would bind or burn out the surfaces. Also, there would be considerable wear and power loss. If the surfaces are lubricated, like the engine bearing, the shaft would float on a film of lubricant. 
The grassy slippery particles of the oil film slide on each other, minimizing friction, wear, and heat generation. An adequate amount of lubricating oil must be fed continuously to the bearing so that a film of oil is maintained in the bearing under all operating conditions.

Function of lubricating oil in an Engine

There are five important functions of the lubricating oil in an automotive engine- 
  1. To minimize friction and wear.
  2. To cool by carrying away heat.
  3. To seal the pistons and thus prevent the escape of gases in the cylinders with consequent loss of power. 
  4. To cushion the parts again vibration and impact.
  5. Clean the parts as it lubricates them, carrying away impurities. 


The magnitude of retarding frictional force mainly deepened upon the following three factors- 

1. Nature of the surfaces

Friction is low when the surfaces are smooth and highly polished. Rough surfaces produce high frictional forces. If the surface is not lubricated then the frictional power will cause damage. 

2. Pressure which forces the surface together

Friction is low when pressure is high. High pressure produces high frictional forces. If the two moving parts are not pressure-fitted with each other then the gap will be created. This gap can create a loss of power generation also. 

3. Kind of material

Friction is low when the material is hard. Soft materials produce high frictional forces.


Oil companies recommend the use of the lightest oil in automotive engines, which can maintain an oil film of satisfactory thickness and provide perfect lubrication. 


1. What is Lubrication?

Lubrication means protecting the two moving parts by providing an oil film between them. Lubrication is essentially required in motor vehicle maintenance. 

2. What is Friction?

Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. When two objects come into contact and one tries to move or slide over the other, friction acts to resist that motion.
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