i was wondering what experiences anyone has had with supermarket fuel?I don't go to supermarket to do food shopping so tend to only go to Shell as its local and as cheap as the supermarkets.I did however fill the tank a few weeks ago at sainsbury's as my girlfriend gave me a 10p a litre off voucher so i thought that's got to be worth it.
After i filled the near empty tank i drove 380miles to Birmingham and back using motorways for nearly all of the journey,i only managed a poor 53mpg which is 15-20% less than i would usually get on a long journey.I then refuelled the car last week with 41 litres of Shell diesel and within a couple of days of doing fairly short journeys my economy was up to 59mpg and i am sure i would get another 5-10% on long motorway journeys.
I have heard that the fuel in supermarkets comes from same refinery as shell,bp,esso etc but it's what each company adds to fuel that differs,so could sainsburys be adding stuff which basicallly waters down the diesel?