Shell or Petronas - no difference in the base oil. They go from the same pipeline from PD to KVDT (Klang Valley Distribution Terminal) somewhere near the F1 Track in Dengkil/Sepang.
Here Shell and Petronas add the additive, or formulation.
What I know is for Malaysia, we import sour crude from middle east, cracked them and produce the different fuel, petrol, diesel, kerosene, lubricants, grease, tar, etc.
This sour crude has high sulphur contents.
Our own sweet crude, we export, why ? more money!
Thus causing problems with our diesel engine no matter how good we maintain them.
I am waiting for a day when JPJ haul a transport operator and he challenge this in court. If he can prove that he has religiously follows the recommended servicing for his fleet of trucks or buses.... the culprit will be .... the oil companies ! yahoo!