The 'E' Type Forum

Hi all,

I have just acquired a S2 coupe and have the pleasure of driving it from Wiltshire to Kent at some point soon. My question is:

Do I need to, or should I definitely add a fuel additive when filling up?

I have no experience with Jags (coming from old Porsche's!) and so will no doubt have many a ridiculous questions coming your way!

Thanks in advance.

Steve.

All Jaguars after ( at the latest) 1967 have hardened valve seats and you can use unleaded fuel without any need for additives. In practice, it seems probable that most engines from 1963 onwards had specially hardened seats, because at that stage California had required all new vehicles to run on unleaded, and since the west coast was a major market, it was uneconomic to differentiate

Steve
Snake oil. The XK engine will run perfectly well on unleaded without any additive. The increase in octane claimed will not be noticeable in performance being only decimal points of increase.
If you are laying the car up for a while with fuel in the tank it may be worthwhile adding a fuel stabiliser to the last fill up.

Good news then - thanks for the swift replies!

I will also heed your advice re the stabiliser.

Thanks again,

Steve.

Steve

As others have said - avoid additives. Suggest you use super-unleaded to avoid pinking if it is a UK car with a 9:1 compression ratio. I believe all XK engines can run on unleaded without modification. This is because the heads are alloy and they used hardened valve seats as standard. Cast iron heads of the period needed lead to suppress wear as the valve seats were not hardened.