95 or 98 RON?

[colski1961]

Dealer told me to run 98 octane only in the Cayman R - others have said 95 will do for normal use. Must admit that I ran my R8 on 95 mainly, without any great loss in terms of performance. Anyone got any guidance as to which to run and/or if a mix (i.e. 'good stuff' every third top up).?

Thanks, Colin

 

[Kumaran.Govender]

That is a good question. I have a vanilla Cayman and always fill up on Tesco's 99. Would love to hear any advice on this.

 

[chrisH]

I have a silver Gen II S and always use 95, neither the colour or the R doesn't make any difference. The R engine is just a slightly higher revving version as far as I know. No doubt this will prompt lots of posts from those using 99 and getting improved mpg over 95, but this is not so in my experience, it doesn't make any difference at all, just costs you quite a lot more per tank.

 

[tscaptain]

I wonder why Porsche put min 98 RON on the filler flap? You don't think they are in cahoots with the oil companies, by any chance...?[]

 

[spyderman]

I always use V-Power but I know that my OPCs cars are only ever filled with 95 RONs.

 

[Buddy]

Generally I fill with V Power and on rare occasions 97 octane never tried 95 in the CS but I did in my previous 986S and found the difference in MPG worth paying the difference, otherwise didn't feel noticeably worse. I did try the Tesco supposedly 100 octane in the CS when that was available and no better then V power.

 

[flat6]

The manual explains the difference. I don't have it to hand but it is along the lines of 'it will run on 95RON as it will retard the timing (anti-knock and all that). So it will run 'fine' on 95RON, but to buy a performance car and not benefit from it's full performance isn't what I would do.

 

[Motorhead]

As others have indicated Colin, your Cayman will run perfectly well on 95 octane as the knock sensors will kick in if necessary to retard the ignition. It really depends how you drive your car - if you're pushing hard all the time rather than motorway cruising or just pottering in traffic, I doubt that you'll notice much difference in performance, or fuel economy for that matter. Also, bear in mind that the ethanol content of 95 octane fuel is likely to increase from 5% to 10% in the near future (see other recent posts on this subject) and this may have an adverse effect upon both performance and fuel economy. I guess that you pay your money and take your choice. Jeff

 

[jhrfc]

V-power, or 98 otherwise. It doesn't make sense to me to have a performance car and then use lower octane (or poor quality) fuel, that will reduce the performance and likely economy as well. not sure if the porsche ECU will also advance the timing back if you put better fuel back in after using 95. Jon

 

[colski1961]

OK thanks all, it's not a cost issue that I'm putting standard Unleaded in the R, it's availability of 98/97 RON where I live, nearest forecourt with V-Power is 30 miles away.....but views taken and I'll try to stick to 'the good stuff' where I can. ps I noted that it was filled/brimmed with standard unleaded (95 RON) when I bought it........seems OPC's don't follow their own guides

 

[John H]

I have run my Cayman for over 40k miles now, almost all of it using supermarket 95 fuel with no ill effects. I occasionally put a tankful of V Power thro it, but mostly for the cleaning effect as it has more detergent in it. I have always thought that any benefit was more down to detergent and cleanliness rather than ron rating. Here's a point though. During the fuel shortages due to the tanker drivers strike some years back, it became apparent that EVERY petrol station in the central belt of Scotland was being supplied from one source, namely Grangemouth refinery. Shell, Esso, ASDA, Sainsurys, Jet, Morrisons, Tesco ... you name it, they were (and still are) ALL supplied from that one refinery. I'm prepared to believe that each version of the fuel may have a different selection of additives, but I am also pretty sure that they all use use the same base stock. This gives the lie to the urban myth that supermarket fuel is somehow bad for your car, when in fact it is all basically the same stock, but tweaked differently. I would guess that the same situation applies all over the UK, as there are only a handful of refineries in the UK. If there is anyone out there in the petrol industry who knows better, I'm happy to be corrected, but until then I'll keep filling up my Cayman on ASDA's finest.

 

[chrisH]

It seems to come down to a personal decision and as I expected there are many who feel they are doing their car good feeding it 98. I tend to go along with the last post. My journeys are mainly on dual carriageways and so are cruising if you're lucky at 70ish. The only time I was able to use the cars performance as it is intended was in Germany where the mpg improved at 100 + when still using 95. My conclusion is you are wasting your money using anything other than 95 on the UKs roads.

 

[spiker]

Guys You own a Cayman don't use supermarket fuel I have had my fuel lines clogged twice with previous cars using fuel from Tesco I always use shell and alternate vpower and fuel save and no problems for the past 3 years

 

[John H]

ORIGINAL: spiker I have had my fuel lines clogged twice with previous cars using fuel from Tesco

I'm sure it is possble to get bad contaminated fuel, but I simply do not believe it has anything to do with it coming from a supermarket. Could happen from any source. I tend to be picky about where I buy fuel, and avoid scruffy badly kept small garages, as I reckon if they can't look afetr the premises, they probably don't care about the quality of the fuel they keep. Give me a clean, well run supermarket with a high turnover any day. I have four cars (2 petrol, 2 diesel) and used to have umpteen motorbikes as well. I have run the lot of them on supermarket fuel for decades, and what must be several hundred thousand miles and never had an issue (fingers crossed [&:])

 

[gmcraib]

Agree with what was said above, its a sportscar so put in the best fuel you can. You probably need a couple of tanks worth for it to change map between 95 and 98 RON (or vice versa) so if you are running 95 and put in 98 briefly you probably won't see any difference. I think mpg is unlikely to be realised as you will be making more power and using it more! I always use V-Power if I can. Super is 97 but I'd consider using Tesco 99 if stuck. Yes petrol (in Scotland) comes from the same refinery but its what happens to it that is different. Its much better in europe they have 98RON readily available, plus the 100+ v power as mentioned.

 

[shorthouse]

Honest John view ... Supermarket fuels - are they that bad? Does your advice regarding the use of supermarket fuels still stand? I understand that you recommend the use of premium fuels (diesel in my case) as opposed to cheaper supermarket fuels for better performance, engine protection, etc. However I saw an Eddie Stobart tanker delivering to Tesco the other day and the driver told me that the fuel was the same as BP. Am I wasting money by continuing to use Shell V Power diesel? Asked on 11 November 2011 by Brian Willett Tags: supermarket petrol Answered by Honest John My advice is to use Shell V-Power petrol or BP Ultimate diesel. Its additive package definitely makes it far superior to any fuel from a supermarket. Most fuelling system problems reported to me are by readers who have been using supermarket fuels.

 

[kristian51]

Supermarket fuel well i have heard lots of ppl and there views on this, but i can give u peace of mind right away. I am a tanker driver and when we pick up the fuel from the refineries it is all the same supermarket fuel is no differnt to shell esso toatal asda or anyone else today my first stop was petrol in tesco then into esso then shell. so although u might have had a bad experience at a certain garage i can assure you supermarket fuel is very safe. just look at it this way tesco an others are so big do you really think they would run the risk of buying dirty not up to scratch fuel an faces thousands in court costs oh an i do use either fuel but can deff see a better mpg with a higher ron fue;l

 

[John H]

Thank you Kristian51 ... another urban myth exploded! []

 

[spiker]

Thanks Kristian You mentioned the fuel was all the same - but what about different RON levels and additives Fuel is not the same

 

[kristian51]

spiker you are quite right ron levels an additives but as someone mentioned further up the thread there a only a few refineries in the uk There are 9 major ones and believe it or not tesco and the supermarkets dont have there own.Although tesco about 6 years ago they did apply to build one on the scotish coast. so not having there own supermarkets buy from the major ones and they are owned by the likes of esso and shell. i was simply saying that if you have 98 ron( 95 96 99 or 100 ron) in tesco it will be no different in additives colour smell how well it explodes to the 98 ron in the esso 200yards up the road but one thing i can bet will be difference is the price, as more than likely it will have all came from the same place.