Supermarket fuel has all the additives/cleaners required by EN standards - the base diesel for all brands is the same, and stored in the same storage tanks at regional/local distribution depots.Just buy good quality diesel which means from Shell, Esso, BP or Texaco.
You don't need any additives.
How do you know that ? Do you know where it comes from, how its refined and distributed and what additive packages are used ??? To many confident statements based on limited data and limited understanding on the Web IMHO.Yes, supermarket fuel is very bad stuff.
The difference can be incredible, even across the same brand. Esso's 99 RON in my closest garage is usually about 8-9p more per litre which, with a discounted fuel card, typically makes it cost about the same as the local Sainsburys, give or take a penny or two. I made the mistake of filling up at an Esso in Portsmouth a couple of months ago and the difference was 17p a litre for the same stuff. I guess it's a supply and demand thing?For me, cost is still the most significant factor and only once have I baulked at the price difference when a local Shell service station just off the A1 was asking 20p/litre more, so I drive straight out and looked elsewhere. On average I pay up to 8p/litre more for premium but this is offset by loyalty points and discounted fuel account cards which knock 5-8p/litre off the pump prices.