fuel - Page 2 - 911/Carrera GT - PistonHeads UK

I'm quite sure that this question has been raised already but here goes. Is there any advantage to fuelling a 991 GT3 with higher or premium octane fuel? Now that the price has come down a bit I feel that I can go the extra few quid.

robgt3 said: I'm quite sure that this question has been raised already but here goes. Is there any advantage to fuelling a 991 GT3 with higher or premium octane fuel? Now that the price has come down a bit I feel that I can go the extra few quid. I'd question why you would fill the car with anything other than Super unleaded, given that is what is recommended by the manufacturer... Do you mean special fuels i.e. 100 RON or do you simply mean Shell V-power, BT-Ultimate etc as opposed to normal 95 Octane? Personally, I'd only ever use anything other than Shell V-power as a last resort - e.g. when in the Hebrides with no other options...!

Waste of money unless you have a turbo where it does give more powe. If you knew how crap 91/93 RON fuel is that these cars are designed to run on around the world, 95 is already a treat.

As already stated, Porsche recommends a minimum of 98ron - why use lower? And before the naysayers chip in, it does make a difference to performance as if a lower octane is used the anti-knock sensors will retard the ignition to prevent damage.

how can they recomend 98 when that's unavailable in half their markets?

They recommend it as that's what the car works best on.

jakesmith said: Waste of money unless you have a turbo where it does give more powe. If you knew how crap 91/93 RON fuel is that these cars are designed to run on around the world, 95 is already a treat. Wrong!

jakesmith said: Waste of money unless you have a turbo where it does give more powe. If you knew how crap 91/93 RON fuel is that these cars are designed to run on around the world, 95 is already a treat. Can you explain why it has a benefit for turbo engines. I can acquire RON 102 at a normal gasstation.(Holland) Thanks

jakesmith said: how can they recomend 98 when that's unavailable in half their markets? I'm sure its available in Hereford which is where the OP hails from.

Always run Shell V-Power in my 997.2 GTS as did the previous owners. Can't see the point on skimping on fuel for your pride and joy. Besides it helped get these for the boys!

<End of thread>

No question rob, always use the highest octane rating you can get admittedly only 98 Ron in the UK. A friend who has just retired from a large oil company, and knows, put me straight some time ago about the differences between the supermarket fuels which lack many of the additives found in the premium fuels. Then there are the Shell power fuels, and his opinion was they were in a higher league than even most of the other premium fuels due the protection they give to engine and fuel line components. As well as the slightly higher octane rating. He didn't work for Shell by the way. Albeit the octane rating is not always the ultimate arbiter of burn limits, it was explained. Expensive car rob. Give it the best you can get hold of.

GT3andy said: always use the highest octane rating you can get admittedly only 98 Ron in the UK. Actually, Tesco Momentum is 99.

Rob, shell v power all the way every time. Grab yourself a shell drivers club card next time you fill up and you can accumulate points and then exchange them for shopping vouchers for Molly - everyone wins

Thanks Guys. The best it is from now on then! Car has now done 900 miles and never ceases to amaze. Inadvertently took it to 8000 rpm in second, I can only liken the engines ability and desire to rev being akin to that of a motorcycle. Still treating it to lots of respect.

Shell is 99 too.

Actually, Tesco Momentum is 99. Well how about that. I stand corrected. Didn't know as don't go to the filling station there. Still wouldn't use it in my car though.

When I picked my car up from OPC Reading the salesman said every 4th fill up use shell otherwise it would be fine on supermarket petrol. Then again he has no vested interest in long term reliability! Edited by LukeS on Tuesday 30th December 20:02

LukeS said: When I picked my car up from OPC Reading the salesman said every 4th fill up use shell otherwise it would be fine on supermarket petrol. Then again he has no vested interest in long term reliability! 95 RON will be 'fine' and won't give you any reliability problems. It will just mean your car doesn't perform as well as it could do and you aren't do my what Porsch recommend. No point in spending that much on a GT3 and then trying to save a few pence on fuel, particularly when people often find they get improved mpg with Superunleaded. Edited by sidicks on Tuesday 30th December 20:25

jakesmith said: If you knew how crap 91/93 RON fuel is that these cars are designed to run on around the world, 95 is already a treat. Indeed - For example, somewhere close to a third of all Porsche cars built Worldwide in 2014 will end up in China, where 91/93 are the norm, you sometimes see 89. Anything above 97RON is unheard of and the quality of the pump fuel is dubious at best in almost all cities, due to the supply chain regularly tampering with the fuel before it gets to the pumps. Whilst in itself this is not a critial issue as manufacturers do a significant amount of testing for this. Cars will run no problem, but rough running and antiknock retardation is often a factor, as well as occasionally buildup of nasty deposits, such as manganese on exhaust valves sometimes experienced in higher temperature/compression engines. A number of manufacturers, BMW for example, sometimes produce specific engine variants for such markets, usually with different mapping and lower compression ratios. All interesting stuff but completely irrelevant to the OP, I know...

Useful info cmoose, but Esso super is only 97.

anonymous said: [redacted] forgive my naivety, what's the effect of ethanol in fuel on engines?

anonymous said: [redacted] You're spot on there BTW I didn't know there was a difference

I didn't know Porsche recommended high octane fuel for the GT3 and this obviously changes things as on my various cars Porsche only recommend 95. I still don't understand how that can really work though as said before the quality of fuels is so poor in large parts of Asia where Porsche has so much of their market I base my opinion on a few things... 20 years of sporadic articles in mags like evo that show that only the turbo cars get a power hike from high octane fuels. Obviously they don't run the cars identically for several 10,000 miles and compare wear so I take that. I also read a thread on here very recently that JZM who are a very well respected Indy garage who I used for many years, are considering a link between ethanol in premium fuels, and bore scoring. Not sure if this affects 991 units or not (yet) I also have a friend who worked as an engineer for a major petrol player for several years and despite my best efforts to coax an answer, would categorically not come away from the company line about the benefit of premium fuels and I judged that as being highly suspect given what she was like, so took that as a pretty clear indicator of their pointlessness, obvs that's just a personal judgement Each to their own but I see it as a waste of money Edited by jakesmith on Wednesday 31st December 10:57

jakesmith said: I didn't know Porsche recommended high octane fuel for the GT3 and this obviously changes things as on my various cars Porsche only recommend 95. I don't know what variants you have owned, but my Gen 1 987 clearly states 98 ron on the filler flap as the recommended octane.

The problem with people trying to judge the difference between petrol fuels is that unless the ECU adaptions are reset for top-spec fuel it will take quite a while for the car to turn the wick up to maximum, so the gradual change won't be noticed. A car run long term on 99RON should show a noticeable difference if you put 95RON in it, but even this may not be all that noticeable if you're not driving it flat-out. If you're not driving flat-out everywhere you should notice improved economy from 99RON, which offsets some of the additional cost. If you want to get the best out of your car I'd suggest filling it with 99RON fuel (or Vpower 100 in parts of Europe - Switzerland has had it for years) and then getting the adaptions reset by a Porsche dealer or specialist. If you do this in conjunction with a service it shouldn't cost anything. BP used to do 102RON fuel (the filling station that sold the most being opposite the Aston Martin factory apparently), which Silverstone circuit used to sell. Since BP stopped it they have it blended especially for them (so their attendant told me), but I've no idea by who or what the ingredients are. Baz from Hartech also explained that using 102 in a car designed for c98RON won't actually reap any rewards and could hamper performance (being too far from what it was designed to run on), but I can't remember the science bit behind that sorry.

Running my Aston on 100 octane fuel apparently meant that it had a 12 to 15 BHP increase. It had been de catted the ECU fettled and was running 200 race cats. Did I notice any difference ? Not really. I just want to know what is the best fuel to put in my GT3 not for a performance gain but for its well being.

The most important factor is to run your car on the very best engine oil and keep it very clean (say change every 6k miles or even less) That will help keep your engine in a much better condition and is a better investment than worrying about the fuel you use (too much) I agree though, the sticker on the filler cap is quite clear, and that super unleaded (shell in my case) is the way to go It really wont hurt though if you put the odd tank of normal unleaded fuel in Generally, I would keep away from cheap supermarket fuel - I don't buy my engine oil or my food at Tesco's, so why subject my car to their fuel.

I've been buying fuel and food from Tesco for years and both me and my cars are still here to tell the story.

Do Waitrose have filling stations yet ?

ArcticGT3 said: Do Waitrose have filling stations yet ? Yes. They sell Shell fuel, at least my local Waitrose filling station does.

ArcticGT3 said: Do Waitrose have filling stations yet ? Yes, and ironically the couple that I have seen are Shell! Perfect

anonymous said: [redacted] Not really. In the USA almost all regions have ethanol in gasoline and there are no reports of fuel system problems related to ethanol. While the pump label gives the ratio of ethanol as 10% my info is refiners are conservative and only add 7% to 8% ethanol to the gasoline. My 02 Boxster has covered over 288K miles and has run ethanol blended premium gasoline (over 8000 gallons of it) and the only fuel system problem has been the fuel pump quit at around 200K miles. The rest of the fuel system including injectors are original. My 03 Turbo has covered just under 130K miles and like the Boxster has run ethanol blending premium gasoline and there have been no fuel system problems.

jakesmith said: I didn't know Porsche recommended high octane fuel for the GT3 and this obviously changes things as on my various cars Porsche only recommend 95. I still don't understand how that can really work though as said before the quality of fuels is so poor in large parts of Asia where Porsche has so much of their market I base my opinion on a few things... 20 years of sporadic articles in mags like evo that show that only the turbo cars get a power hike from high octane fuels. Obviously they don't run the cars identically for several 10,000 miles and compare wear so I take that. I also read a thread on here very recently that JZM who are a very well respected Indy garage who I used for many years, are considering a link between ethanol in premium fuels, and bore scoring. Not sure if this affects 991 units or not (yet) I also have a friend who worked as an engineer for a major petrol player for several years and despite my best efforts to coax an answer, would categorically not come away from the company line about the benefit of premium fuels and I judged that as being highly suspect given what she was like, so took that as a pretty clear indicator of their pointlessness, obvs that's just a personal judgement Each to their own but I see it as a waste of money Edited by jakesmith on Wednesday 31st December 10:57 It is not a waste of money using the specified octane of gasoline. Using the right octane grade of gasoline allows the DME to use the most optimum ignition advance timing which maximizes the amount of mechanical energy that is obtained from the burning of the gasoline. Using a lower than specified octane grade of gasoline in these engines is false economy. While the initial out of pocket expense is less, the engine is less efficient burning this sub-par octane fuel and gas mileage suffers so one is buying more of lower octane fuel and more often.

Ethanol in fuel is not good for older cars, especially if they sit for any period of time .... These are cars that have rubber components in the fuel systems that are not ethanol resistant. Typical problems are fuel lines swelling. / failing ..... Seals in fuel pumps etc.. I run all my 'classics' in she'll v power or equivalent as they have the lowest levels of ethanol , normal 95 typically containing 10% Old V-power was ethanol free, had tried to get an answer on its new formulation so interesting to hear it's at 5% Modern cars with modern ethanol resistant rubber should have no problems really