.............. Asda finest two star..................
No such thing as Asda finest when talking about their fuel. Try it on some decent juice from BP or Shell and see the difference.
I am doubtful of claims like that. It is like wine tasting, even professionals fail in blind tasting trials. Now if there is a blind study that shows supermarkets fuel is worse, fine, but if it is just best on subjective experience, I have my doubts..
Higher octane rated fuel is obviously needed for engines in a high state of tune, but for most road going engines any old petrol will do. I suspect the supermarket fuel comes from the same refineries as all other fuels. BP or Shell might put different additives in, but I think there is quite allot of woo around additives as well. Until I see a proper study showing they actually have any benefits.
Put it another way, I have never noticed any difference between any of the fuels I have used. Granted I have never owned a car with a high performance engine in a high state of tune, but for a normal road car any old fuel will do.
My main catchment area for vehicles I maintain includes two Asda superstores, one near my home, the other near my place of work. Numerous times, and usually in clusters of several cars at a time over the space of a few days, I will receive calls from owners who are experiencing odd losses of power, misfires or rough-running on their vehicles, almost exclusively petrol-fueled. I always ask first where they last refueled their vehicles and they have ALWAYS refueled at one of these two supermarkets. Once I have found this I ask them to fill-up with branded fuel and - with only one exception where a coil pack was failing - filling up with BP, Shell , Esso or Texaco has fixed the problem and additionally it is usually repaorted that the car is now 'running better than it ever has'.
I used to firmly believe that 'fuel is fuel is fuel' and it all comes out of the same pot until my old Peugeot 306 (XUD9 non-turbo diesel) started to run less well, knock more and occasionally cut-out when cold. with 150,000 miles or so on the clock I put this down to perhaps needing the injectors overhauled. Then I tried some BP diesel in the tank and almost instantly the problems went away, much quieter and smoother running, less smoke, better acceleration and no more cutting-out. Oh, and an improvement of at least 100 miles from a tank of diesel, yielding approximately 700 miles per tank on BP as opposed to approximately 600 miles on supermarket diesel. The engine has no electronics to adjust or tune itself so it can't be that. Also worth noting that if I lend my car to someone and they put some supermarket fuel in the tank, I can tell that they have. At 50MPG and branded fuel at 3p / litre more at the pump that makes the branded fuel cheaper than the supermarket fuel.
Sadly I have ten years of fuel data to back up this claim, with graphs, that shows the step-change when the swap to branded fuel was made. You or your vehicle may see different results of course.