In the manual of my 1987 XJS V12 it mentions that the car needs 90 octane. But there is a major difference between European rating and American rating with European 95 being more or less equivalent to 87 American octane. Does anybody know if the manual relates to European or American octane?
Thanks,
Daan

 

My 87 US spec owners manual says 87 US octane is what is required, but I still run premium. And 87 US octane is closer to 91 Euro not 95 Euro.

Jon

 

North American spec HE cars don't need premium, which I always found odd as the Lucas cars have 11.5:1 compression. I run premium in mine.

 

I run our 98 octane, BUT we got the 12.5:1 engine, so choice is a no brainer, albeit $2.54/ltr bites a tad hard.

 

^^^
And here we are complaining about our local $6/gal for premium!

 

Try 8 dollars a gallon equivalent here!

 

does the 12.5:1 version require premium? What does the manual say?

98 ron is equivalent to 93 in North American gas.

Canadian taxes have slowly driven our prices up as well. 91 (AKI) is over 2$ a litre here.

 

I am "breaking in" my 39k XJSV12 1987 garage find, which went through a long process of restoration. It probably had not been run for 10 - 15 years as it was abandoned in a large storage facility. When it finally ran, it had a loud knocking sound and I feared some of the valves were damaged. But my mecanic told me to drive it for a while with injector cleaner, which I did, while using 94 octane. After about 300 miles the knocking sound had disappeared! I will continue high octane gas with injector cleaner, but maybe after a thousand miles, I may first stop using the injector cleaner and yet another 1 or 2k miles use a lower octane fuel. I am a very conservative driver and avoid fast accellerations or high rpm. I just want my car to look pretty . I guess that when the engine has been properly cleaned, my driving style does not really require the highest octane.

 

Your car your choice.

NOT MINE TO DICTATE.

Run the highest octane available at the pumps. We NO GOT Ethanol more than 10% readily available (85 is a look and hunt task) down here, whoopee,, and I run our none laced 98 in all of them, no matter the engine, or the book.
Books CANNOT be updated, common sense, and the info is based on what was the brew of the day when it was printed.

Injector cleaner, is a bottle a month in ALL mine, Infected or Carbied, its just a habit from the Redex days, like a meat pie without sauce, yuk.

I buy the stuff by the carton, whenever its on special, and brand means zilch, its the same stuff inside.

Never replaced, or cleaned, any Injector in all my years. The Carbied beasts are always clean as new whenever I need to look inside the bowl etc.

Driving it as you are is my strong advice. The V12 was built to RUN, and RUN HARD. So when you and the care are better aquaited (AKA the warm and fuzzies), Vegas and back, the BEST thing you could ever do for the beast.

 

I will take the advice on the octane, but I drive my 3 oldtimers, my 1987 Jag, a Citroen prestige 1987 and my Buick 1930 with tender care. I consider the all museum pieces that should be passed on to next generations of car enthusiast after I pass away. So I drive them on cruise control as much as I can, don't accelerate hard, while I enjoy the envy looks of modern car drivers, as my jewels gently slide along the roads.

 

God for you.

That will workwell with teh 3 you mention, but the V12 being an "over square" engine will labour at that.

It was design to run, and rev.

All my Jags since day 1 were Daily Drivers, and we lived miles (in those days) from anywhere, so pedal down and get on with it was the flavour of any trip. Mostly on unsealed roads.

I still have some of the early beasts, allocated to the kids, and stored in a barn for when I go on that big trip. They look after them, its the deal.

The best is the 85 XJS, that sucker took us twice around our island coast road (25K kms each time), and was the best road trip/s we did before age got us, not the car.

 

As you wish but, actually, you're not doing the engine....nor future generations.... any favors.

Cheers
DD

 

I let all mine kiss the Red Line every shift just to keep the spider webs out!
(';')