Fuel

[Matt-Rallye]

Run a bit of bio in your hdi every so often that'll clear it out 

Then just use asda fuel. ;

 I'm not entirely clued up on diesels as it's the devils fuel but for petrol using too high an octane such as v power on an engine nit mapped for it will loose power. Don't worry gti6 owners because you have a knock sensor I'm sure the default values are higher hence the positive feedback ffom momentum 99 
However engines like the k series or tu that don't have a knock sensor will be best suited for 95 octane

Just use AvGas.