Yes.
First hand experience several years ago - destroyed the engine in 4-5 oil changes..
As for profit margin - correct. In real oils, the profit margin for shopkeepers is not much. But in fake oils it may be upto 50% of the retail price (I studied the market recently and know what I'm talking about).
Now consider the two scenarios ;
1- you sell a bottle of oil and make 100 rupees
OR
2- you sell the bottle of same label oil, and make 480 rupees
Unfortunately there aren't many shopkeepers who would turn down that tempting proposal of 480 rupees.
So yes, the odds of getting a fake oil from any given shop are more than the odds of getting the real oil.
