Most high street petrol stations (Esso, BP, Shell) get their fuel from UK refineries. The quality of this fuel is high as the standards set by the UK refineries is high. All this fuel is essentuially THE SAME FROM THE SAME REFINERIES but each supplier will add their own additives. Although no refinery adds enough detergent to protect your valves completely.
Supermarkets buy there fuel from whereever it is cheapest. This often means it comes from outside the UK (although it can come from UK refineries if the prices is right or suplies are short elsewhere) and can be from places like Eastern Europe. Because the quality is not assured to as high a standard as in the UK refineries, the supermnarket fuel can be of lower quality (ie it isnt refined to as stringent a temperature band and as a result has more impurities). Also their is often less emphasis on adding quality additives to reduce price.
RON (research octane number) is actually less important to the motorist than MON (motorist octane number) as RON is measured under low load, but MON is measured under high load (as knocking is more likely to occur under high loads i believe). The octane number at the pump is actaully the AVERAGE of these two figures, not the actaul RON of the fuel. But this is beside the point as the fact remains that if the RON of two fuels are the same they can still differ in quality (ie their refined state).
Ever wondered why people in the middle east like to drive Mercedes? Its because the engines run well on the sh*t fuel. The same sh*t fuel that could go to a supermarket pump in the UK. Common for supermarket filters to have all sorts of sh*t in them INCLUDING SAND. Ok the filter has removed it before it went in your car, but you see what im saying.
If you dont care about your car feel free to use supermarket fuel.
Anyone got a burger, havnt eaten in five minutes?
