Time to flash Stu's rule of him being always right.
I dont know too many details in this.
However i will share one thing which i experienced with my petrol engine.
With Indian Oil, petrol i get a little of higher mileage as compared to petrol from HP. However apart from mileage there is no other difference as far as i noticed.
I have not tried any premium so far, as i dont want my engine to have bed of roses and be habituated to that.