Mk3 cupra - Octane (RON)

[RasmusDC]

i live in Denmark, and have a Cupra on the way.

we mostly have 92-95 octane (ron) petrol, only Shell station has higher (99 octane Vpower) that costs a bit more, and not many stations around.

i´ve had Diesels for the most of my car life, so never put anything into it, but saw that CUPRA = 98 recommend but it runs on 95..

and then read "scary" threads about loosing 10-15% power and having a "poor" running engine on 95 octane, is that really true?...

saw a fifth gear test were a Impreza lost 25 HP on 95 octane.

so i´m getting a bit scared, since i don´t want to be running around searching for the FEW stations that can fill my car with petrol, and paying the price for cars in Denmark that we do.. i really don´t want to pay 5-8% extra for my Fuel on top of that.

 

[morini]

i live in Denmark, and have a Cupra on the way.

we mostly have 92-95 octane (ron) petrol, only Shell station has higher (99 octane Vpower) that costs a bit more, and not many stations around.

i´ve had Diesels for the most of my car life, so never put anything into it, but saw that CUPRA = 98 recommend but it runs on 95..

and then read "scary" threads about loosing 10-15% power and having a "poor" running engine on 95 octane, is that really true?...

saw a fifth gear test were a Impreza lost 25 HP on 95 octane.

so i´m getting a bit scared, since i don´t want to be running around searching for the FEW stations that can fill my car with petrol, and paying the price for cars in Denmark that we do.. i really don´t want to pay 5-8% extra for my Fuel on top of that.

I have run all my cars up to now on normal 95 octane. However, if you look at syphons RR thread you will see a photo of inside fuel filler cap it recommends 98. I'll be sticking with 98 when I get mine, though it'll probably be Tesco momentum rather than vPower as my mrs spends so much cash at Tesco we usually always have money off fuel vouchers.

You can bet the full tank the dealer has promised will be 95 though!

 

[bluenose172]

I've said this in another thread... From mapping Subaru ecus this past 5 years and knowing the ecu logic they use when low octane fuel is used, I'll be using 99 Ron in my Cupra when it comes. Although you might not 'feel' it believe me the ecu will pull timing (thus be down on power) if it has been developed to run on 98 and above.

 

[Crafoo]

Chances are running on 95 when it states it should be run on 98 will just make it run badly.

As others have said it'll result in a loss in power.

 

[Dan FR]

it wont run badly, just won't run as much timing as it could.

Stick with Vpower, Tesco's 99 is rubbish in comparison in terms of preventing knock.

 

[morini]

it wont run badly, just won't run as much timing as it could.

Stick with Vpower, Tesco's 99 is rubbish in comparison in terms of preventing knock.

You've depressed me now. These days Tesco is anywhere between 10p and 20p per litre cheaper, depending on how much of my hard earned the mrs has given them for groceries last shop. Lat time I filled my car it was 20p off and it's hard to turn that price difference down.

Don't know if it's true or not, but I read somewhere that all the petrol stations will get deliveries from the same refineries so what you get in the supermarkets is the same stuff as you get on the branded esso / shell etc forecourts anyway. Not sure if I believe that though.

 

[bluenose172]

I never saw an appreciable difference between shell and tesco 99 on knock levels.

 

[Crafoo]

I think Tesco fuel gets a lot of bad chat about it and it seems most people shun it in favour of shell, I've never noticed a difference between the two, apart from cost, my current car is running well on Tesco 99

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[sootytorques]

Agree with crafoo, no noticable difference shell VPower versus Tesco 99, just the price & with fuel save its even more appealing over shell.

 

[Scott Millar]

It's a case of each to their own. If your happy putting 95 or Tesco 99 or Vpower then do so. All cars must be designed to run on the standard 95 in standard setup so your car will run fine on normal 95 and the difference will hardly be noticeable in terms of power unless your looking to improve a quarter mile time etc.

Personally, I run my car on Vpower because I can afford to do so but having used periodically 95 in the past I'm happy to report the car ran just fine and I didn't notice any power difference.

 

[AndrewJB]

Stage2+ LCR runs very well on Momentum 99.

 

[Crafoo]

I wouldn't say it's designed run on 95 if it clearly states in the filler cap that it should be run on 98/99.

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[markpile]

It will run on 95 as any car will the difference is at what point the duel will detonate at 98 will compress more than 95 so you get a cleaner burn and you use more of the combustible fuel when it's squashed more in the cylinder head so good fuel economy too

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[Dan FR]

Well I log my car a lot with VCDS, and tried a tank of Momentum 99. I had to turn the timing down a notch on the Revo map to bring the CF back to an acceptable level.

Do some research in to it and draw your own conclusions, info concerning resistance to detonation is available online, more to it than just the RON

 

[simonali]

My nearest Shell station is a 50 mile round trip so it's out of the question for me. No one sells 98 fuel in the UK anyway, do they? Most super is 97RON.

 

[J888ohn]

Always buy Tesco regular diesel, never had a problem with any of my cars and the one time I tried an experiment with Shell fuelsave diesel I actually got worse MPG! Was doing the same trip for two weeks from home, up the motorway to college and back again in similar weather. I work around Grangemouth and all the tankers come out of there no matter what their livery is. Very much in the camp of why pay the money grabbing oil barrons (and government!) a penny more for the same stuff.

 

[yellowcone87]

There are only two varieties of 99 Ron unleaded available in the UK. Shell VPower and Tesco Momentum. I have used both in my Nissan Qashqai and financially, neither made much sense. I noticed an average improvement in economy of 2mpg over a full tank. Performance improvement was slightly better, but still hardly worth raving about. However, my Nissan has been designed to run on 95 Ron, so its unlikely the ECU will have known what to do with the improved fuel.

When I owned my Ibiza Cupra, many moons ago, it had been designed to run on 97Ron, which at the time was the highest quality available. The difference when running this engine on 95 or 97 was far more noticeable. The car just wasn't happy on 95. It was measurably slower, and around 15% less economical.

In my experience, if your car has been designed to use 97 or 99 Ron fuel, you really should stick to it. It will be better on economy on the right fuel anyway, which will help offset the extra cost of super unleaded. Yes, you can use 95 Ron, but be prepared to suffer the consequences for doing so. If however your car doesn't require higher octane fuel then you usually are better off overall sticking with the 'ordinary' 95Ron. You just won't see the benefit... Unless you can afford to buy whatever fuel you like! In which case, why not enjoy the slightly better performance of 99.