# Fuel - High Octane or NOT?



## hunaink (Feb 15, 2016)

I wanted to get everyones opinion on this as a trip down to the mechanic led to a lecture!

So he banged on about how the turbo engines not only require high octane fuel to produce the best results but also using high octane fuel can decrease wear & tear on the engine!

What have you guys found in your experience? Do you guys always go for High octane or is supermarket fuel exactly the same and this is just one of those "gold plated HDMI" fads?

(I have a 2.0TFSI)


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## Danny1 (Sep 2, 2010)

hunaink said:


> I wanted to get everyones opinion on this as a trip down to the mechanic led to a lecture!
> 
> So he banged on about how the turbo engines not only require high octane fuel to produce the best results but also using high octane fuel can decrease wear & tear on the engine!
> 
> ...


I only ever use tesco 99 momentum, worth every penny and has been proven many times over, always run that or v power imo.


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## Grizzlebear (Oct 2, 2015)

I know the difference with a tdi using shell v power.


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## sieuk (Mar 14, 2016)

Ive only ever used Tesco momentum in my TTS but on previous cars going between standard fuel and 99 is really noticeable it just seems more responsive.


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## Dash (Oct 5, 2008)

Says in the manual that you can use 95 RON, but at the cost of power. The TT is meant to use 98 RON.

My MK1 certainly notices the difference. I'm not even going to try 95 in the RS.

You'll get better fuel consumption too, but it won't be so much better that it'll cover the extra cost.

Premium fuels like She'll also have additives that will keep your engine cleaner over the life time. The success of these claims though are hard to demonstrate. Still, given how Tescos take short cuts on most their products, I can't imagine their super unleaded is as good as branded.


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## TT-driver (Sep 14, 2010)

Turbo or not: what counts is if the engine mapping can take high octane into account. If it can, then the engine will run more efficiently on high octane. If it can't high or normal octane will make no difference.

For the first gen 2.0 TFSI Ron 98 is recommended. Ron 95 is allowed, however the engine will run less efficient.

Engine wear isn't really influenced by octane. Oil and oil service have a larger impact. What does help are the cleaning agents. They keep the injectors clean. Clean injectors vaporise fuel better. As a result the fuel burns better and less deposits are formed.


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## Hoggy (May 8, 2002)

Hi, As above, designed for 98+ octane so use it.
My 225 has never used anything but Optimax/Vpower & a 30 mile round trip for it.
Hoggy.


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## hunaink (Feb 15, 2016)

Awesome guys, think its unanimous! Just went on a data logging session with dash command plugged up on iphone & got a reading of 211bhp on a non mapped 2.0TFSI. Thats the first time i've run it on VPower (with a load of Forte cleaners in it!) but i've only had it a couple of months. Vpower it is from now on!

Thanks, H


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## BlueMagic (Feb 14, 2015)

hunaink said:


> Awesome guys, think its unanimous! Just went on a data logging session with dash command plugged up on iphone & got a reading of 211bhp on a non mapped 2.0TFSI. Thats the first time i've run it on VPower (with a load of Forte cleaners in it!) but i've only had it a couple of months. Vpower it is from now on!
> 
> Thanks, H


I would not rely on an iPhone app for power readings . . . .

You need to use a rolling road, ideally on the same day at the same time so that the atmospheric conditions are the same, colder temps will lead to denser oxygen levels in the air which in turn lead to more boost/power on their own.

Anything other than that will have too many variables and just be a plain guess.

That said, it's been proven a thousand times over, if an engine's map has the ability to adjust for higher octane fuels, it will sense it and adjust accordingly.


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## hunaink (Feb 15, 2016)

BlueMagic said:


> hunaink said:
> 
> 
> > Awesome guys, think its unanimous! Just went on a data logging session with dash command plugged up on iphone & got a reading of 211bhp on a non mapped 2.0TFSI. Thats the first time i've run it on VPower (with a load of Forte cleaners in it!) but i've only had it a couple of months. Vpower it is from now on!
> ...


Thanks! Never thought about all the additional variables that could effect.


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## CWM3 (Mar 4, 2012)

I use V Power in my 20 year old lawn mower, and no fancy mapping on that puppy, and its never thrown a paddy, so I am sure your advanced Bosch electronics will manage to cope with whatever you pour in the tank.


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## hunaink (Feb 15, 2016)

CWM3 said:


> I use V Power in my 20 year old lawn mower, and no fancy mapping on that puppy, and its never thrown a paddy, so I am sure your advanced Bosch electronics will manage to cope with whatever you pour in the tank.


Haha with all these added benefits everyone is claiming it has, i might replace my water intake with vpower!


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## andez1781 (May 27, 2015)

hunaink said:


> CWM3 said:
> 
> 
> > I use V Power in my 20 year old lawn mower, and no fancy mapping on that puppy, and its never thrown a paddy, so I am sure your advanced Bosch electronics will manage to cope with whatever you pour in the tank.
> ...


If you are looking for reasoning behind the higher octane fuel it is because of the high compression the direct injection engine can provide, the higher the octane the more compression the fuel can take before ignition and in turn provides more efficiency , that's why it's recommended and the engine feels better for it .


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## Fioretta (May 19, 2016)

Only had my 2.0 TFSI for 4 weeks and just started using Super Unleaded from Sainsburys and I have definitely seen improvement in performance and consumption.


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## WoRkZ (Sep 19, 2015)

andez1781 said:


> If you are looking for reasoning behind the higher octane fuel it is because of the high compression the direct injection engine can provide, the higher the octane the more compression the fuel can take before ignition and in turn provides more efficiency , that's why it's recommended and the engine feels better for it .


Thank you for posting this *andez*! I was beginning to think nobody would explain it fully. But yes, high performance engines, especially turbos, are equipped with knock sensors that will advance timing a bit if the fuel is detected as having spontaneously ignited before the spark set it off. The car then keeps this timing for a while (some will try dialing the timing back once the ECU sees a big fluctuation in the fuel level, others will automatically have a go after a while or a combination of both). So once you put better fuel in, it will eventually get back to full power, but maybe it won't do it immediately.

That being said, I ran my Focus ST for two years on regular petrol... and the car ran perfectly fine the whole time... but with reduced power of course. In that case, I did that deliberately because the car was too powerful for it's 2WD setup and chewed through tires like an excited puppy through a pair of snickers.

But the TT, especially the Quattro, can handle all the power available... so unless you are flat broke, give it the best available fuel for sure.


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## Trackdaybob (Jan 30, 2015)

Super unleaded for me (well the car but you know what I mean :wink: ).


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## technik21 (Mar 6, 2016)

Reminds me of the time when I was on a weekend break, and desperately looking for a Shell garage that I knew was hiding somewhere nearby, and only had 5 miles worth of remaining fuel showing on the DIS! All in order to get some VPower fuel!!

Can't remember when I put anything but VPower in my cars


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## hunaink (Feb 15, 2016)

technik21 said:


> Reminds me of the time when I was on a weekend break, and desperately looking for a Shell garage that I knew was hiding somewhere nearby, and only had 5 miles worth of remaining fuel showing on the DIS! All in order to get some VPower fuel!!
> 
> Can't remember when I put anything but VPower in my cars


I think i might be the same! After one full tank of vpower, my sister put in £5 of Essos Super unleaded to get to work and back & the loss in power i felt was very obvious!

Back on the Vpower, hopefully engine will realise its on the good stuff again and adjust back!


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## 8JVR6 (May 13, 2013)

There is really two main point to choosing fuel types:

Octane: which is essentially detonation resistance. High compression engines require higher octane, as there is more heat and compression in the cylinders. If you put a lower octane fuel, the engine will start pulling timing in a high compression engine and there will be power loss.

If you have access to Vag com you can monitor your timing pull, if you are at 0 retard. Added higher octane gas will not do anything, if you are at -1 - 2 it's pretty normal. Anything lower -3 -4 there will be a power loss and you need a higher octane.

Ethanol content: fuels with ethanol have less energy than fuel without ethanol.

Sent from my iPhone using Tapatalk


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