I personally feel that there are differences in the grade and brand.
Tried the S** bec I got 10% on my credit card....but can feel the 'jilt' in my auto gear change....as in not so smooth....
and when I go Malaysia, I'll pump the Sh*** XO, which is bloody expensive at abt RM 1.80/l (but still much CHEAPER than S'pore price!).....and can feel the 'power' altho my is just a 1.5 corolla...
so now I'll pump half tank of the 10% discount type, with another half tank from my usual Blue station with 6%....so that will have an average discount of abt 8% lor......
my 2 cents....
: dun call me cheapskate