This has probably been done to death before, but I can't seem to find it.

I want to look at changing which type of petrol to use.

Two main questions ( I Might be being really thick here so bear with me)

Do I have to drain the tank to fill up with new petrol or can I just mix with what i have in the tank already. Will this make much odds to performance/MPG.

Secondly, which is the best value for money to use.

P.S I live in Essex if that helps.

Cheers

Si

Just wait till the tank is nearly empty and then refill with the new fuel you to use. Mixing it won't do any harm, but you obviously won't see the full change until all the old fuel has passed though.

wait untill you get to a minimum of 1/4 then fill it up what optimax or what ever fuel you want to use then go driving you should start to see the difference once you reach the half tank marker. Ive just done the same my self so no need to worry really

In the vehicles at work, we always just use the Regular Unleaded, but one day i thought i would make my work splash out so i filled up with the Excelium Unleaded @