This brother has actually pointed out a very basic but yet very little known fact. Selecting an oil is actually more of a combination of things that give you the idea of which oil to use. There are two major things to understand; Engine temperature and ambient temperature. 0W, 5W, 10W deals with viscosity (higher being more viscous). The slippage performance required by the engine when its first turned on while it is cold. 30, 40, 50 deals with temperature both when engine is warm and the ambient temperature in which the car is operating. Newer engines should use 5W or 10W. Once over 100K Kms switch to 10W is recommended. In Pakistan the way climate is, 40 is more suitable.
All companies have different additives in their engine oil so its all about selecting a suitable grade and then stick with it.
Please note that Toyota somehow are making their customers to shift to Toyota Petron 20W-50 oil (they make more margin on it). Do not use that oil. I have received cars in my garage which just crossed 125K kms and under the tappet cover their engines have soot and grease deposits on the engine internals (20W is the thickest grade oil being produced). In just a few more thousand kms I know these engines will start to smoke. The problem is you cannot make them switch to lesser grade as it will make the car to burn oil even earlier as engine internal tolerances have been reduced already. This is a heads-up.
