A lubricant is a substance introduced to decrease frictional power and heat generation between the surfaces in common contact when the surfaces move.
A good quality lubricating oil generally has the following properties:
Table of Contents
Appropriate Viscosity:
The viscosity of oil should not alter with rising in temperature.
Oiliness:
It ensures adherence to the bearings and spread over the surface. This property makes oil smooth and very vital in boundary lubrication.
Strength:
The lubricant must have a high strength to avoid metal contact and seizure under high loads.
Chemical Stability:
The lubricant should not react with surfaces and any deposit in the cylinder.
Pour Point:
It should be low to allow the flow of lubricant at a low temperature to the oil pump.
Flash Point and Fire Point:
The lubricating oil should not burn within the cylinder, otherwise, it will leave heavy deposits and poisonous exhaust. Hence, the flashpoint and fire point of the lubricating oil should be high.
Neutralization:
The oil should not have a tendency to form deposits by reacting with air, water, fuel, or the products of combustion.
Cleaning:
The oil should act as a cleaning agent inside the engine and should carry any deposits with it. It should also have non-foaming characteristics, low cost, and be non-toxic.