Hi guy's
Long time since i'v been on, so ok recent events had me buying an O2 sensor, due to the P0430 code,........ which was not needed ! The garage i use are a really good bunch of guys , i have been using them for years and i trust them, they tell me today that before they changed the sensor for me they did a omissions test like they do for the MOT......both sides where perfect, so they cleared the code and asked me what petrol i use,... premium as i have always done for years with all my large engined cars, well apparently the "S" after 1999 was designed to run on regular 95. I have had a small issue with her running a little warm, and i am thinking that maybe the premium fuel is the course of this....i did say "maybe"....and the guy at the garage did say the cats where very hot.......so what do you guys think..? change to regular 95 or what...?

 

95 is all it needs (as handbook etc say). More is OK but a waste of money.

It's odd to get a code that appears unwarranted - and that one like many others only flags if it occurs twice under similar conditions (and otherwise is silently deleted before flagging).

I'd check fuel trims (see the many threads) in the hopes of gaining useful data.

Possibly do a smoke test but the data gathering is (almost) free and most folk don't DIY the smoke test...

I don't see why anyone really thought an O2 sensor would be the cause (you won't see a lot of people on here who've found that!).

hmm... though it just about could be an O2... which one on that side did they change?

(I'd still go for trims...)

If the trims show nothing, the next thing is probably to watch the O2 waveforms - each side should be like the other and the downstreams should have quite flat waves.

 

Jag v* is correct as usual, using anything more than 95 RON or 91 AKI is a waste

 

85ron -> 95 ron

 

Quite right, I've corrected my post above. Thanks.

 

Hi JagV8.
it was the engine light that cam e on throwing up the P0420 codetelling me the O2 sensor was faulty...but on further digging it also was saying an electrical fault was to blame, anyway, i have dropped £30's worth of 95 in this morning , aaaannnnddddd!, one thing i noticed after half an hour was that take off...very responsive ,but that is about all i have noticed, we are having a good run out tomorrow to Snetterton....about a 300 mile round trip , so she will have had a good run on 95 and i will stick with it now......thanks for the advice.

 

If I read correctly, you've always used 95 octane in the car and nothing else. If so, I don't understand the references to regular and premium. The names mean nothing, only the number.

 

Hello , i have used 98 premium since i have had the Jag , and have always used it in all my cars that have performance or large engines, but in this case i have now discovered i do not need to use it , regular unleaded will do fine, i have had the Jag sine October last year, and have been using premium , i thought it was clear what i had written.....? anyway ...code cleared , now running on regular (95).

 

I wasn't aware that the marketing terms regular or premium were still used in the UK. I though only the octane number In RON was shown on the pump.

Regardless, use of 98 was not the cause or solution to your issue.

 

Is this true in a 2006 4.2 L NA too?

 

Here in Germany the petrol stations have their own name for premuim petrol nowadays depending on which firm you go to too. By one firm it is Vpower and anothe ultimate. 95 octane is known by all as super. Never used this petrol with 10% ethenol so dont know what it is called.

 

Yes.

95 RON (or, I gather, 91 AKI).

 

Fuel here with 10% ethanol is call E10 and is also identified by the appropriate octane rating (AKI system as used in N.America). Some vendors also add misleading or confusing marketing terms like, premium, super, extra, max power etc. etc. All very confusing to non enthusiasts.

 

Explains it nicely.
https://www.simplemotoring.co.uk/car-fuel-types/

 

Thanks for that but unfortunately it's full of technical errors that just confuse the issue even more.

High octane fuel is no different in ignition properties than regular. The only difference is resistance to detonation, a whole different thermodynamic process. The article also goes on to promote the concept that premium fuel with fancy names like Vpower with even higher octane numbers have additional super powers. Hogwash- they don't, as has been proven many times over.

 

Ahh but they have to make more dollars out of the punters. I think an extra 10p or more a litre makes it pointless for most people. With a well maintained car and I pop a can of injector cleaner in every 6 months there is no point paying over the odds per litre kidding yourself it's better for the car.

 

I am a little disappointed with this thread having decided only yesterday to start using Shell V Power. This is of course only an experiment and I expect to experience improved fuel consumption, cleaner whatever, improved sex life, and at the very least increased odds on winning the National Lotto! OK it was only a whim and with double the Shell Clubcard points, perhaps worth it, time will tell.

 

All petrol/gasoline has the same amount of chemical energy, irrespective of octane level. There may be slight difference in the additive packages from one brand to another, but any result would not be visible for many thousands of miles. BP Australia says 3,000 KMs.

 

Does it take the same distance to improve his sex life?

 

They say you should consult a doctor if the effects last longer than four hours.