Octane/RON, etc

I run my RS6 on nothing but V Power (previously Optimax).

Surely your manual tells you what to use?

-- Mike Smith

Mike your right it should do - and I will check when I pick the car up next week, unless anyone within the group can enlighten me :)

However, although an engine maybe designed to run on 95 RON the ECU may be configured to permit a higher octane fuel that fires at a lower temperature that claims to give you a cleaner engine and slightly better performance.

I was only looking for an opinion from seasoned owners who may claim that advances in fuel - like V-power - may provide better mileage, acceleration, etc than the 95 RON the manual may suggests.

Sorry if I was vague.

Mick

I believe that most Audis (as sold in the UK) are designed to run on

98RON, but with the ability to use 95RON with some degredation in performance.

I know VW/Audi engines (as with many others) can vary their spark timing/mixture a bit to compensate for *lower* octane ratings than those recommended; for instance, my '03 Passat's manual recommends that 90+ AKI be used (roughly equivalent to 93 or 94 RON IIRC) but states that lower octane can be used with some reduction in performance. But I don't know whether they will take advantage of higher octane ratings than the recommended value.

-- Mike Smith

Thanks for the info.

I think I will try V-Power - as the guy with the R6 states and from what Peter claims, however, I will try and keep track of mpg, etc and see if the extra cost is worth it.

Will let you know if interested.

Firstly, what does it say on the inside of your fuel filler flap, and owners manual? If it says something like 98RON recommended,

95RON if 98 not available, then 98 RON is what it will run best with (better power and/or better economy, dependant on driving styles, vehicle loading, etc, etc, etc).

Regarding UK SuperUnleaded - it is NOT consistant like it is in mainland Europe (there SuperUnleaded is a minimum 98 RON), ours can vary from 97-99 RON, from different oil companies. My observations are:

not available (standard 95 unleaded): Asda, Jet, Morrisons (Texaco supplied), Murco, Power, Safeway, Texaco

97 RON: BP Ultimate, Esso, Tesco SuperUnleaded (some-being phased to 99RON), Total SuperUnleaded 98 RON: Shell Optimax (phased out to V-Power), Q8 SuperUnleaded, Sainsburys SuperUnleaded 99 RON: Shell V-Power, Tesco SuperUnleaded (only where pump shows 99)

The following PDF from Thorney Motorsport makes very interesting reading, particularly when looking at the M3 CSL results. Firstly, from approx. 2,700rpm onwards, 99RON gives a clear Torque & Power increase over 95RON (obviously) and 97RON fuels. Secondly, from about 5,000rpm on, BP Ultimate (97RON) AND Shell Optimax (98RON) appear to make identical Torque & Power figures, even though there is supposed to be a difference in Octane Rating. I guess maybe BP Ultimate has to meet a minimum of

97RON, but is actually formulated closer to 98RON, (or even Shell Optimax didn't quite make 98RON!!!).

Being as Tesco 99 is cheaper than V-Power, my money goes on Tesco

99 Super Unleaded. If I turn up in an area where Tesco is still selling 97RON, then I look for Shell V-Power.

Incidently, Tesco 99 contains 5% bio fuels, for those with a "greener" consience!

Regards

Sean '03 Audi B6 S4 4.2 V8, '06 VW Golf V GTI 2.0T FSI

That's certainly the recommendation for my RS6 and, I believe, most other current Audi models. (as I stated in my previous messages)

[Snip]

Yes, I've seen John's report before. The suggestion that Optimax didn't achieve 98RON is worrying when Shell claimed a minimum of 98.4.

Well, my local Tesco in Reading is four miles away, the other side of town, and my local Shell is half a mile away. At our other place, in Norfolk, the nearest Tesco is 20 miles away (and I'm not even sure it holds 99), whereas the Shell is about five miles.

Thanks Sean - to date I have been using V-power but will check out your links.

Any other thoughts welcome.

Mickx

I personally avoid regular 95 unleaded if at all possible in both the GTI and my S4 V8. Both are recommended for 98RON, but will run on 95 - whenever I have put 95 you really can notice the difference, particularly in power and general drivability. I've never compared fuel consumption though.

To be honest Mick, I would hazard a guess that any of the 98/99 ron fuels, from either the major oil Co's, or the supermarkets would be much more responsive/economical/drivable than using the quality, ie only branded oil company regular 95 ron unleaded. The 3.2 V6, even with the FSI isn't particularly economical, when compared to say the 2.0 FSI turbo. That was one of the crucial factors with the wife's new Golf - it was a toss-up between a high-specced GTI or the R32. After having long test drives in the R32, the GTI, and also the A3 3.2V6 and A3 2.0T FSI, and not really finding that much more power from the R32 or the A3 3.2, we went for the GTI.

The following link gives *some* of the current locations for the

99RON super unleaded at Tescos. I quote *some*, because the web-site seems to miss out whole chunks of the UK - Scotland, Leicestershire, the West Midlands, Warwickshire, to name a few! I don't know what neck of the woods you are, but if you are in an area which they have missed from the list below, the fire up M$ Autoroute, and you can actually search for Tesco petrol stations, by county if needs be. Find a couple of your local Tescos, and the next time you pass by or need to fill up, try them out. Unfortunately, you have to drive up to the pumps (unless you have your pocket binoculars to hand) to see which brew of super unleaded they dispense, because the large price boards will just quote the price of "Super Unleaded", (along with normal unleaded & that smelly oily stuff!).

Another good reason for using Tesco 99, is that it is always cheaper than V-Power, and much more cheaper than BP Ultimate, and if you spend £50 on your weekly shopping in Tesco, then you get a further 5p a litre discount! Every little he.... - NO, i'm not doin' their ruddy advertising :-o

Regards Sean

Thanks Sean - am in Bournemouth, so plenty of local Tesco's.

Will do the V-power vs. Tesco challenge :)