Does any one know whether there are any ill effects with running Premium Fuel as opposed to Premium Unleaded in a fully decatted UK spec MY00. Is unleaded really necessary if there are no cats in the system?

ttt

If they are the same octane rating then stick with unleaded. We have a problem here getting high octane unleaded so alot of people use leaded.

The lead is said to affect your spark plugs which would probably need to be changed sooner (~25000km). Also if you have the standard pass through Lambda sensor it will become contaminated over time. You need to change this to a lead compatible sensor. All depending on the amount of lead in your leaded fuel of course. It has been said that lead can affect the coatings on the pistons and other components. Havent heard of any incidents of this though.