aye supermarket crap is bottom of the barrel
read a report on supermarket fuel, very interesting as major suppliers such as shell and esso etc put additives in the fuel to increase octane and keep it at a level for a period of time where as supermarket fuel they get it at discounted rates without certain additives
all fuel loses its octane rating if left for a period of time just supermarket is even worse at that
my experience with supermarket fuel is that i get through it a lot faster than other fuel companies and i notice loss in acceleration