2012 Jaguar XFR reccomended fuel

[liner33]

I have just bought my first Jag , a 2012 XFR which i collect this week, The dealer has let me take the manual and it does say that you can just use regular 95 petrol but is this correct? Many years of owning modified Japanese car and even my daily driver Skoda has forced me to use Super unleaded and preferably 99 octane so Tesco and Shell , is 95 really ok for these engines ?

[philmots]

I'm sure 95 is fine, but I use Shell V Power in mine, mainly for the cleaning properties rather than any potential increase in power.

[fatboy b]

Congrats on the purchase. I've just picked up, an R-S at the weekend. It was pre-filled with 95, and I've topped it again with 95. Seems to be ok, but I will try a tank of super next to see if it makes a difference. Regarding the cleaning side of things, I avoid supermarket fuels, as the main brands do have detergents in, unlike supermarket fuels.

Also, drop by www.jaginfo.org and say hi. Plenty of advice & banter over there

Edited by fatboy b on Monday 3rd October 06:35

[jamieduff1981]

philmots said:

I'm sure 95 is fine, but I use Shell V Power in mine, mainly for the cleaning properties rather than any potential increase in power.

Same here in my R-S. I have used 95 when there's been no Super available and the car was absolutely fine with it, but I tend to use branded Super unleaded a) because I can afford to and b) because rightly or wrongly, some people claim this engine can coke up so I use the branded super unleaded for the cleaning additives.

[verynicechap]

I've just run through a tank of V-Power and i'm sticking with it as i believe gives a noticeable difference even over the Tesco 99 stuff. It certainly feels that way.

[8bit]

jamieduff1981 said:

Same here in my R-S. I have used 95 when there's been no Super available and the car was absolutely fine with it, but I tend to use branded Super unleaded a) because I can afford to and b) because rightly or wrongly, some people claim this engine can coke up so I use the branded super unleaded for the cleaning additives.

Correct me if I'm wrong but my understanding of direct injection engines is that because the fuel goes direct into the cylinder (so after the inlet valves) rather than into the inlet manifold runners, so it doesn't clean the inlet valves, which is the bit that's susceptible to coking. VAG have had issues with this because they have a PCV system that just vents air and oily vapours from the crank case straight back into the intake so the vapours gather in the intake valves.

I gather Jaguar have a system which collects oily vapours from the PCV system and feed them back into the engine heads - the workshop manual for the 4.2 X150 XK/XKRs at least confirms this. If that is the case for the 5.0 engines then detergent additives in the fuel won't make any difference to the coking but the PCV oil/air separation will. That's not to say the detergent properties of better fuel won't have benefits elsewhere though.

I'm not disagreeing or splitting hairs, just wondering if the belief that the DI Jaguar engines are susceptible to coking is off the back of documented evidence that some VAG DI systems have shown problems - have you seen anything solid proving the same for Jaguar engines?