• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

High test or regular gas?

Share this page

C

Coastalman

Jedi Warrior
Bronze
Country flag
Offline
Hello to the Jaguar forum. I have owned many British cars over the years, but never a Jaguar. One of my fellow car enthusiasts has a 1990 V12 XJS that I am considering buying. It is fuel injected and requires High test gas. Is there any way to tune the fuel injection to run on a lesser octane gas? I like the car, but the price of high test gas is so much more than regular that I am afraid I would tend to drive the car less often than my Healeys. Also, is there anything special about this Jaguar that would make it better or worse than other XJS models. The car has only 40,000 miles on it and if in very good running order.
Thanks,
Charlie
 
Why V-12 if detuned, six would have more power? you can drive without high test but pinging in these aluminum engines will kill them quickly. High test gives you better fuel mileage, which is a complaint of these cars. If you drive it occasionally you will not feel the price difference. I drove mine for 5 yrs. to and from work and to Fla twice and it really isn't bad on the pockets. I averaged 20mpg at 75mph from St. Louis to Fla. with 2 tanks. My 2 MINIs do the same, two tanks. Detune if you must, but you will coke the engine and rebuilds are in the thousands not hundreds.
 
Good information Larry. As I said, I have not owned a Jaguar before and do not know all the ins and outs like I do for Healeys and MGs. If I could ask another question of you, what should I be looking out for as I evaluate this car?
Thanks,
Charlie
 
Check all rocker corners for any signs of rust (bubbling in paint, etc.). Look close around front and rear windows. Look at front cross member as this is the lowest part of car and collects a lot of stuff from road. Look under rear assembly and check rubber mounts ( these degrade wether you drive it or not ). Exhaust not real hard to find but a pain to replace. Check under floor mats in front for clogged A/C drains, will be damp or rust coated. Boot (trunk) check for fuel smell , check carpet extending under tank for wet. Engine, check for oil leaks and any noise associated with cam, valve wear. Oil sender is in valley near firewall, check for leaks. Look under car for oil leaks as there are cooler lines with rubber O-rings for seals. While checking front underneath look at radiator bottom, these mounts collect dirt and rust. Windows, slow, clean mechanisms and relube with light grease. I know it is a friend, and the car is in a garage most of the time, but sitting really degrades these cars. They need a high speed run every week to keep things flowing. Look carefully as the body panels are not readily available yet.
 
Back
Top