STR Fuel Grade

[Martin15]

Hi.
I am about six weeks into ownership of a 2007 STR. Can someone tell me what is the correct fuel grade I should be using? The fuel flap sticker is missing and I cannot find any other information in the owners manual.
I have read magazine articles that say (For later supercharged models) they are unhappy with anything less than Super Unleaded. I have so far used super unleaded which the STR appears to be entirely happy with.
Any other thoughts on fuel variants would be helpful.

Best regards.
Martin

[J44EAG]

Montana 5 (Doug), as an STR owner himself will most certainly have a totally accurate answer for this. Here is mine.

I would certainly be running any supercharged car on premium fuel. Even with a reflashed naturally aspirated model I do that myself. The extra octane in premium fuel is there to help reduce any possibility of cylinder detonation at high load, pressure and engine speed. This is often known as an anti knock property and useful in high compression or forced induction equipped cars. Antiknock additive also helps keep charge air as cool as possible where a carburettor installation exists.

Our engines have an anti knock sensor which may cut in during hard driving. The sensor will retard ignition timing and perhaps adjust fuel mixture to prevent detonation. My reflashed V8 runs very differently when premium fuel is used. It is smoother, has a faster pick up, is a little quicker throughout the rev range and will rev slightly higher and more willingly when premium fuel is in use. In a supercharged situation, antiknock control is even more important so using premium fuel is to be recommended.

You can help your car greatly by using premium fuel which is less likely to damage engine internals for the above reasons. As a starter I would also annually add a bottle of Cataclean to a low filled fuel tank to help keep catalytic converters as clean as possible and help prevent blockage from accumulated combustion by-products. The brew does work extremely well and many of us have noted our cars run more happily after this preventative maintenance addition.

Mike

[thomas45]

Ok a bit off subject but here is the dumb-ass question which has baffled me for as long as I have been here. What is an STR and how is it identified?

[J44EAG]

Slang for S-type R. Red R badges on boot lid and lower front wings. Montana 5 has a superb example. MY 2002.5 to MY 2008.

Mike

[Montana5]

Jaguar recommend 95, though (they also say 98 can be used) the Engines and ECU are built for 95, only a remap with 98 in mind would change things. Personally I have tried Super Unleaded a few times and not noticed any difference, though I would say that 95 was slightly more economical and cheaper to buy. I try to vary from Supermarket to branded as much as possible. Some of the STR and XJR Supercharged Owners on another forum I use, meet at Santa Pod a few times a year, none of them have ever noticed an improvement to their timed runs, with 98.
Hope this helps.

Doug.

[Montana5]

Ok a bit off subject but here is the dumb-ass question which has baffled me for as long as I have been here. What is an STR and how is it identified?

It used to be quite easy to spot an S Type R, they were the only S Type to have the Mesh Grille fitted as standard and the Badges above both front wing repeaters and on RHS Bootlid, however with the 2004 facelift, Badges were removed from the wings and Jaguar started to fit the Mesh Grilles to other models. Front Seats have an embossed 'R' on the Backrest below the Headrest. Earlier models 2002 to 2004 had the Spitfire Wing type Bootlid Spoiler which overhangs the rear wings slightly, whereas the facelift had a shorter Bootlid Spoiler with no overhang. Probably the best way to identify a stationary STR is by the Brembo Brakes.

Doug.

[thomas45]

Thanks to Mike and Doug,I get it now and had a good look at Dougs STR,
magnificent !

[stypesteve]

Hi, I own a 2.5 and the only fuel I use is Shell V Power, can highly recommend and I get in return more mpg. Very good.