Properties of Good Lubricants

A lubricant is a substance introduced to reduce frictional force and heat generation between surfaces when they move in mutual contact.

A good lubricating oil generally possesses the following characteristics:

1. Suitable Viscosity: Oil's viscosity should not change with a temperature rise.
2. Oilness: It ensures adherence to the bearings and spread over the surface. This property makes oil smooth and is very important in boundary lubrication.
3. Strength: The lubricant must be strong enough to avoid metal contact and seizure under heavy loads.
4. Chemical Stability: The lubricant should not react with surfaces and any deposit in the cylinder.
5. Pour Point: It should be low to allow lubricant flow at a low temperature to the oil pump.
6. Flash Point and Fire Point: The lubricating oil should not burn inside the cylinder, otherwise it will leave heavy deposit and poisonous exhaust. Therefore, the flash point and fire point of the lubricating oil must be high.
7. Neutralization: The oil should not tend to form deposits by reacting with air, water, fuel or combustion products.
8. 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, be low cost, and be non-toxic.