Tesco Momentum vs. Shell V-Power

[tekkendp]

I have always used Tesco Momentum on my car. And it has been perfectly fine. This week I was running low, and shell was closest, so I did a full tank on V-power. Now I suddenly having hot start issues. I wasn't last week. Weird hot starts. If I drive the car to temperature, then stop for about 5 minutes or so, the car has hot start issues (with the Shell fuel). If the car is up to temp, and I repeatedly stop start the engine, it's fine. I car is perfectly fine on Tesco fuel, no matter the temp.

I doubt my car engine would degrade that quickly. So, the only thing it can be is the fuel. But from what I understand, Shell is meant to be better quality fuel. So what's going on?

I can't wait to finish this tank and go back to Tesco fuel. But does anyone have any suggestions? Has anyne seen anything like this before?

[AndyBrad]

bad batch?

[Dazza44]

I' run mine on bp ultimatum,and.often v power with no issues, without playing the ,maybe it could just be coinsidence, run in out go back to previous fuel see if problem.persits if it does maybe compression test.

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[Ainmhidh]

Completely guessing here (how much of the v-power tank did you get through before any issues?) The V-Power cleaning agents might have dislodged some crap in the engine that is causing the issue? or maybe something is tuned to the one fuel type and slightly struggles to handle the different stuff?
Be interesting to see what happens when you go back to the Momentum...
I generally also use BP Ultimate and/or Shell V-Power. Had to part-fill with BP standard recently - it doesn't sound quite the same (I think?) but it pulls about like usual.

[WildMan10]

Nothing weird about switching off then immediately starting fine. Most low compression engines will do that.

It won’t be the brand of fuel. There’s something else going on.

[Dazza44]

And most run fine on 95ron,after all ,even states that as a minium inside the fuel cap cover.

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[acegeezer]

Personally I don't like V Power and neither does the car, she starts better, pulls better with smoother power delivery on standard 95ron.. absolutely no need for higher octane.. from my experience anyway
I guess this thread will now trigger a pissing contest between fuels

[tekkendp]

Thanks for the help guys. Plan of action:-

1) Use multimetre to check battery (car is still using original - and this winter has been pretty cold)
2) Cataclean (the tank is almost empty anyway)
3)Get Nick to cast his eye over it - leads, plugs, etc....
4) I'm not going to say rebuilt, but restore to it's former glory

[WildMan10]

I guess this thread will now trigger a pissing contest between fuels

No need for that. There really isn't much difference between the Super options; run what suits your tastes. Standard unleaded will give you a little less mpg, a little less power and a lower cost per mile, but runs a higher risk of detonation that will ruin Apex seals before you can say 'ting'.

That said. I prefer Shell and BP, which seem to work as I don't have those horrible gummed up valves that you see in the ads.

[SeeJay]

I once tried a tankful of V-Power in mine,and it ran rough,felt less responsive and generally made driving the car a less enjoyable experience

My tipple of choice has pretty much been Esso Ultimate 97RON,which the car seems to thrive on. On the odd occasion when I've had to tank up with something else,I've found BP and Texaco don't have any adverse effect on the car...I guess she just don't like Shell

[acegeezer]

I guess this thread will now trigger a pissing contest between fuels

No need for that. There really isn't much difference between the Super options; run what suits your tastes. Standard unleaded will give you a little less mpg, a little less power and a lower cost per mile, but runs a higher risk of detonation that will ruin Apex seals before you can say 'ting'.

That said. I prefer Shell and BP, which seem to work as I don't have those horrible gummed up valves that you see in the ads.

[SeriousSam]

To add a counterpoint, I once filled my car with Morrisons 95, and it ran like a bag of spanners. Pretty sure I was getting detonation at the top end, and it was certainly very harsh and unpleasant anywhere over 6k. Mine doesn't seem to mind most big-brand fuels, but I've got into the habit of running it on V-Power and I kind of like scoring the extra airmiles when I buy a tank, so that's my choice. Also my closest garage is a Shell, which helps

[qwakers]

in my short time owning a 8 ive run through all the options, premium 95ron supermarket 95, tesco 99, v power and bp.
i could tell no difference between any of them. same mpg, same performance.

maybe my car is just a oddball, but there you are, we all make our choices... mine is asda 95.

[PeteH]

No need to say "no need for that" either.. it was a tongue in cheek comment nothing but a funny.. jeez some people, even you put up a choice Ian

I think Ian was just saying "No need for a pi##ing competition". I don't think he was saying there was no need for the post.....

[WildMan10]

Indeed, I was saying that there was no need for a plssing contest. I hadn’t realised that the wording was unclear, so, for the record, I have no issue with acegeezer’s comment above it. I’m relaxed about the later comment, presumably now edited out, unless I can get a drink out of it . . .

[warpc0il]

For the record, mine was very happy on Shell V-Power or Tesco Momentum, until we moved over to NI in 2015

Shell doesn't exist over here and Tesco stopped selling Momentum here back in 2012 - apparently they keep having to tell people that there's no demand

The only premium fuel available is Sainbury's Super Unleaded, which is only 97/98 RON.

However, I understand that many of the premium fuels now contain more ethanol than they did before 2015, so my pre-move results may not apply now.

I came across this "league table" that suggests that Sainbury's are still getting their higher octane from a better base, whereas Shell and Tesco are perking-up theirs with ethanol, though it's only a tiny sample.

http://www.ethanil.co.uk/league-table/

[Dazza44]

Ok silly question is a higher ethanol % worse or better?. ( I was looking at the link

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[PeteH]

I think most car manufacturers say anything up to E10 (10% ethanol) is fine to use. Ethanol is very effective at stripping the lubricants from surfaces, so things like injectors start to see high wear with large ethanol content. It also causes rubber to soften and swell, so seals and hoses suffer.

Some engines are designed to run on high ethanol content fuel, and these need to use special seals, hoses and injector internals.

The benefit is a massive increase in knock resistance. This would seem to be a huge benefit on rotaries, that will destroy themselves if they knock.

E85 is sometimes used on high compression race engines, if the rules allow. It's obvious, because it smells very distinctive........

[Dazza44]

Thanks for explaining that Pete

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[SeeJay]

Pete,a big part of the Nissan GTR tuning scene in the states is 'E85 flex fuel'.. many GTR guys run this fuel mix - 85% Ethanol - to give a pretty impressive power gain,alongside what they call 'full bolt-on' mods - exhausts,downpipes,injectors,intakes - from what I've read on the GTR Life forum,no-one has mentioned seal/hose/injector issues...

[delta0]

Cleaning capabilities and knock protection are the 2 main reasons I use super. I normally use Momentum.

[Mistry93]

From memory, doesn't the RX8 ECU learn according to your driving style and fuel type? If so then if you 'tune' or consistently use a particular fuel then suddenly switch fuel with a different composition, it may affect the map thus, a slight performance change. I've seen this happen when I have been to the dyno when building racing cars at university.

All in all, if your car is running fine on a particular fuel then I'd say continue using, as long as it is >95% octane.

I could be wrong and if I am then ignore me.

[warpc0il]

Some engine management systems will try and push the envelope by advancing the ignition until knock is detected and then back off a tad, to get the maximum out of the fuel being used. In these cases, a sudden change to a lower octane fuel will cause a big power reduction as the anti-knock response over-compensates.

However, because the rotary engine can be destroyed by detonation (caused by pre-ignition) the Renesis PCM is much more conservative and keeps well away from any potential knock-inducing conditions. The dynamics of the rotary also means that there's no significant power gain from advancing the ignition, unlike a piston engine.

[PeteH]

Pete,a big part of the Nissan GTR tuning scene in the states is 'E85 flex fuel'.. many GTR guys run this fuel mix - 85% Ethanol - to give a pretty impressive power gain,alongside what they call 'full bolt-on' mods - exhausts,downpipes,injectors,intakes - from what I've read on the GTR Life forum,no-one has mentioned seal/hose/injector issues...

Most modern injectors are ethanol compatible, but it is a subject that injector manufacturers consider. Injector specifications will usually quote ethanol compatibility. The other issue with ethanol is that it absorbs water, unlike petrol. So bits of your fuel system can go rusty if they are not designed with ethanol compatibility in mind.

Don't get me wrong, I'm not saying ethanol will create problems. I'm just pointing out things to consider before deciding to use high amounts of ethanol.

[warpc0il]

Ethanol defiantly causes problems with classic cars and bike, as the materials used in the fuel lines, pumps, seals, carbs etc, was never designed to be ethanol resistant and, in most cases it isn't, even at the low levels we are now starting to see in UK pump fuels.

The RX8 was designed and most were manufactured, before ethanol became a significant factor in the markets in which the car was sold. There is no mention of ethanol resistance in any of the original or subsequently released service publications. However, this is also true for most cars produced in the early 2000's and that's why there's a limit to the ethanol permitted to be added to standard pump fuels. We may start to see some garages offering higher-ethanol fuels as an alternative, as they do in the US, though this can cause all sorts of miss-fuelling issues and confusion.