What do oil grades mean?

Ratings denote the quality of engine oil. So, what do these numbers mean?
Engine oil grade

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Choosing the right grade of motor oil for your car can be confusing. But using the right grade is vital for the durability of components as it reduces wear and tear. Cars have rated grades for engine, transmission and other oils. And numbers like 10W-30 or 0W-80 may puzzle you, but  are easy to understand.

Multi-grade oils work over a temperature range unlike single grade oils. In a rated grade like 20W-80, the ‘W’ specifies the minimum temperature the oil can function in. The 20W means signifies the minimum temperature for ideal viscosity of the oil is 20 degrees Celsius. The ‘80’  denotes the maximum temperature of 80 degrees Celsius. An improper grade of oil will not be viscous enough and will cause components to overheat and damage them.

Here are some tips while choosing the oil:

1.    Check the grade of the oil and ensure that it is approved by SAE International.


2.    Select the grade specified by the manufacturer. The grade of engine oil is different from transmission oil or gear oil.

3.     Consult manufacturer/dealer for the ideal grade of engine oil for high performance cars.

4.    Different components have different grades. Refer to the users’ manual for grades of various oils. Transmission oil has a higher temperature range than engine oil and cannot be used in the engine.

5.    Petrol and diesel engines need different oils. A diesel engine uses heavier, thicker engine oil than a petrol motor.

Follow these tips for a long and trouble free experience with your car’s engine

Posted on 23 Aug 2012
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