Supermarket fuels

Frozennova said:
Take any car on the market, especially a turbo/supercharged one and map it on Supermarket 95RON and Dyno it then fill it with 98/99RON and Dyno it, you'll see more power and torque through the entire rev range with higher octane as it's got higher knock resistance
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That's not what he said though is it? He said there was a difference between supermarket and branded fuel. No one is arguing there is a difference between 95RON and 98/99.
 
If supermarket fuel was rubbish, then why would the other garages not promote the advantages of their own?

I always fill at the same garage, which happens to be my ASDA supermarket; have done for 25,000 miles of the cars ownership. Its a diesel without DPF, I just use redex fuel treatment every few tops ups.
 
shifty_uk said:
No, there's 2 Asda petrol stations on my typical routes, one doesn't even have a premium unleaded pump. I've never used supermarket premium unleaded fuel before(I stick to branded) so I'm not sure of the quality
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That still makes no sense, why would the 98 octane fuel be of worse quality than the 95 octane fuel from the same source? The only possible issue is that fuel stations sell less 98 than 95, so the 95 should be very 'fresh', but that applies to all fuel stations, not just supermarkets.
 
Weirdly on the other side of the coin I started using V-power and it gave me nothing but problems EML and a death of a lambda sensor
 
i seem to get less mileage if i use morrissons diesel. so i dont go there if i can help it.

coming home drunk in a taxi one night i asked a taxi driver if he thought some fuels were better than others and he said stay away from tesco and morissons.

i know this isnt anything to really go off but them taxi drivers do some miles and will probable know better than most of us.
 
koooowweeee said:
i seem to get less mileage if i use morrissons diesel. so i dont go there if i can help it.

coming home drunk in a taxi one night i asked a taxi driver if he thought some fuels were better than others and he said stay away from tesco and morissons.

i know this isnt anything to really go off but them taxi drivers do some miles and will probable know better than most of us.
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Because driving a taxi means you understand chemical engineering.
 
Dogbreath said:
That still makes no sense, why would the 98 octane fuel be of worse quality than the 95 octane fuel from the same source? The only possible issue is that fuel stations sell less 98 than 95, so the 95 should be very 'fresh', but that applies to all fuel stations, not just supermarkets.
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Pricing, I pay the extra for V-power because of its reputation and I like it in the car. I'm not going to pay the extra for supermarket premium so long as I know that my car gets filled with quality V-power 80% of the time. As someone else pointed out, Asda don't even sell premium so it's probably a case of not seeing a pump, too.

Update
Anyhoo, in the interest of keeping this thread updated, I emptied the tank on a run this morning, brimmed with V-Power along with a bottle of Redex advanced(I know, I know!) and what a bloody difference. No stuttering starts, 'misfires' under load and the car is generally more responsive and powerful.

I still think this might be hiding an underlying issue with the fuel lines/pump/injectors so I'll keep an eye on it. If the fuel turns out to be the issue, can't believe I've never made the connection before.... but why would you?!
 
Noticing that big a difference from just one tank seems abnormal to be honest? Normally you'd need a couple of tanks for it all to adjust and cleanse itself of the old fuel iirc. So yeah, sounds like a component in your car is playing funny games.
 
[TW]Fox;28849150 said:
Because driving a taxi means you understand chemical engineering.
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You don't need to be a chemical engineer to see injector issues running one fuel & not another, not when your cars are going through a set of injectors every 6 months. I'm not saying the taxi driver did know anything, but I've drawn the same conclusion from knowing the owner of a taxi business for 7 years & seeing a correlation between Tesco fuel & injector failure.
 
mrk said:
Noticing that big a difference from just one tank seems abnormal to be honest? Normally you'd need a couple of tanks for it all to adjust and cleanse itself of the old fuel iirc. So yeah, sounds like a component in your car is playing funny games.
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Well he said earlier that the car requires 98, so I'm not surprised it runs like crap on 95, not sure why the big mystery :confused:

Run the car on the fuel it tells you to, simple surely?
 
Your car sounds broken. Even regular fuel in the UK is some of the best in the world. There is no way a fault free standard UK car would behave like that purely because you didn't use V Power.
 
Iamzod said:
The girlfriends parents have several MK3 Mondeo TDCi's some with lower mileage than mine & some with higher but they always use Tesco fuel because it's cheaper whereas I stick shell V-Power in mine as the price difference is minimal & it's convenient as the fuel station is on my street basically.

I don't get any power or MPG advantages over the normal stuff, but what I do get is a car that has never had injector failure, whereas every single one of their cars has needed replacement injectors, some of them are on their 3rd set.

There is probably nothing in it but for a few quid a month i'll stick with the premium stuff.
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How many miles per annum are they doing tho?

If they're doing 5,000 miles a year in a diesel and you're doing 25,000+ then they've probably got ruined injectors :p
 
Kenai said:
Well he said earlier that the car requires 98, so I'm not surprised it runs like crap on 95, not sure why the big mystery :confused:

Run the car on the fuel it tells you to, simple surely?
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Well my car manual says it recommends 98 too, but it will run fine on 95 for normal driving. Hell the fuel filler cap sticker says only use 95 to 98 unleaded fuel. All it means is the car will perform to book specification when used with the recommended fuel grade.

So given that info, I'd expect to see slightly lower MPG and slightly lower performance, but not much, using 95 over 98.

It just sounds like his fuel filter/injectors or something else in the fuel system is dirty.
 
mrk said:
Well my car manual says it recommends 98 too, but it will run fine on 95 for normal driving. Hell the fuel filler cap sticker says only use 95 to 98 unleaded fuel. All it means is the car will perform to book specification when used with the recommended fuel grade.

So given that info, I'd expect to see slightly lower MPG and slightly lower performance, but not much, using 95 over 98.

It just sounds like his fuel filter/injectors or something else in the fuel system is dirty.
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There is a difference between recommended and requires, a turbo is more likely to be required than recommended because of the increased chance of knock that isn't there with a NA engine.

What the manual says for your 3.2 NA has no relevance to a 2.0T engine.
 
2 litre turbo engines, especially VAG ones, are used in mass market mainstream applications. They are not specialist high performance enthusiasts engines. It would be counter productive to the manufacturer if it ran that badly on 95 Ron fuel. Running best on 98 doesn't mean misfiring and running like its broken in 95.
 
Edit* What he said^ :p

Kenai said:
There is a difference between recommended and requires, a turbo is more likely to be required than recommended because of the increased chance of knock that isn't there with a NA engine.

What the manual says for your 3.2 NA has no relevance to a 2.0T engine.
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But if we take that literally, then the media would be awash with an uncountable number of people complaining that their turbo powered cars feeling like they are broken after using 95 octane supermarket fuel.

This simply is not the case. Op's car does have an issue.
 
[TW]Fox;28849362 said:
2 litre turbo engines, especially VAG ones, are used in mass market mainstream applications. They are not specialist high performance enthusiasts engines. It would be counter productive to the manufacturer if it ran that badly on 95 Ron fuel. Running best on 98 doesn't mean misfiring and running like its broken in 95.
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I don't know what version of it he has though, if it's just a boggo 200hp one then yeah, if it's one of the variants in an S3 or something then I wouldn't be surprised to see a requirement for 98 at all, to maintain the higher level of tune.
 
EVH said:
How many miles per annum are they doing tho?

If they're doing 5,000 miles a year in a diesel and you're doing 25,000+ then they've probably got ruined injectors :p
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They are doing about 50-60k a year, depends on the car as some of them have more than one driver using them, some of them have injector failure within 20k miles of having them replaced which is crazy really when mine have done 100k and are still fine.
 
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