Having recently acquired a 1956 model XK140 DHC which the previous restored fairly extensively, he recommended the use of a fuel additive to compensate for un-leaded fuel use.

We use the highest octane fuel usually available in UK (97/98 RON) but we are not aware that the engine (valve seats) has (have) been revised in any way.

Is it recommended to use an additive of a type approved by FBHVC ?

Jerry

Hello Jerry,

There is no need for fuel additive in the XK engine.
They all had hardened Valve seats from day one.
But be sure to use 95 RON or higher ( we can't get lower than that anyway in the EU )

Regards,
Peter Jan
XK140fhc, XK150Fhc, S-type 3.8

Back when Jags were first made and raced all fuel was unleaded. In the 60s-70s when they added lead they raised the price for adding lead. Then in the 80s when emissions were instilled they took the lead back out and raised the price again. There is no need for additive but should use best grade fuel, as the new alcohol induced fuels have lower
octane. Octane additives have been proven useless, were tested and actually lowered fuel octane. Put in the highest grade fuel and enjoy your ride. If you get any pinging, these older Jags have a knurled knob on distributor to back or increase timing in increments to eliminate pinging, that way you could drive thru different highlands and lowlands and countries without fuel concern.

Thank you for those responses, that is most re-assuring.

Jerry

if, for USA, folks, you have 10 percent ethanol fuel..add an ethanol fuel treatment product..like Starton, Stabil Marine for ethanol, or other similar brands..in the mfg recommended amounts.