Fuel additives

[delta0]

BG44k. This I have found is the best cleaner.

 

[Ryan-3]

Maybe try a couple of full tanks of VPower - it won't be much more expensive than buying a fuel additive.

Best way to do it. Also means a higher RON fuel for initial running with the cleaning properties to remove deposits. Few tanks of this and a good fluids check. Should be fine.