# E10 petrol



## Blacklab! (Feb 24, 2020)

So from September the new E10 petrol is being used. I have a 2002 TT 225 Bam engine, so can I use the new fuel or will I have to use the E5 (old stuff) ? :?


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## David C (Apr 15, 2013)

You should be using Super Unleaded anyway and that is remaining as E5.


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## Hoggy (May 8, 2002)

Hi, As above.
Hoggy.


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## Blacklab! (Feb 24, 2020)

Yes I am using super unleaded. So basically we cannot run on E10? Just reading an article that says older cars will cost approx £6 more to fill up. Ah well its a classic anyway.


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## David C (Apr 15, 2013)

Blacklab! said:


> Yes I am using super unleaded. So basically we cannot run on E10? Just reading an article that says older cars will cost approx £6 more to fill up. Ah well its a classic anyway.


It typical tabloid reporting written to cause anger and panic.

Super Unleaded is not changing.
Is is E5 and is remaining E5.

Basic 95RON Unleaded is currently E5 and is becoming E10, a change that was announced several years ago.

All Mk1 TT (except the 150) are mapped for 98RON Super Unleaded, so no change.

150 Roadsters are mapped for 95RON, so those will have slightly higher bills if they want to stick to E5 by moving to 98RON.


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## Hoggy (May 8, 2002)

Hi, Most vehicles from 1996 onwards shouldn't be affected by the corrosive effects of Ethanol on rubber, plastic brass etc
It will still absorb moisture so the lower the ethanol the better.
Hoggy.


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## StuartDB (Feb 10, 2018)

Why do mappers love E85 if E10 is too much Ethanol.


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## David C (Apr 15, 2013)

StuartDB said:


> Why do mappers love E85 if E10 is too much Ethanol.


From a mapping and max BHP point of view, the issue isn't the % of Ethanol, it is the Octane rating.

ie 95RON E10 v 98RON E5

Race E85 is 104RON.


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## EricNL (Mar 13, 2021)

According the German Audi site all TT's can use E10 fuel.
E10 is not applicable for some early TSFI (A3 A4 A2) engines and for cars with stand heating.

WBR Eric.


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## PlasticMac (Apr 25, 2017)

As DavidC says, there is confusion around E numbers (E5 & E10 etc) and Octane/RON.
The E number is the % of ethanol in the fuel.
The Octane/RON is not related to the E number.
Ideally, our cars should be run on 98/99 octane. In UK, 98/99 happens to be E5, while 95 octane is E10.
Most cars of recent vintage are designed to run on 95 octane, and are compatible with 10% ethanol.
A few (and my A2 FSI is one), but not our cars, are incompatible with E10.
Since there's a commitment to preserve availability of E5 for now, this is done via Super Unleaded. Box ticked.
If you want to run your pride and joy on 95 octane, and save a few pennies, that's your choice. I'll stick with V Power.
Mac.


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## orangecurry (Jun 21, 2020)

not quite - the E number is the *maximum* percentage of ethanol that may be in the fuel.

ESSO have jumped on the misinformation about ethanol being a *really* bad thing, and are now promising 0% ethanol in their E5 labelled premium fuel. Which, by the way, is available only if the ESSO branded pump is near enough to a Greenergy distribution point.


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## John949 (Apr 12, 2017)

> From a mapping and max BHP point of view, the issue isn't the % of Ethanol, it is the Octane rating.


Not quite:

If the calorific values of the fuels are the same then the one with the higher octane rating would allow you to advance the igniton further and probably gain power.

If however the fuel with the higher octane rating had a lower calorific value then you'd probably be better off with the lower octane fuel. As it happens fuels with higher octane ratings tend to have a higher calorific values (which accounts for the general misconception that octane rating is related to power). The most well known exception is LPG, which has a very high octane rating but a low calorific value. Running your car on LPG gives about 2/3 of the mpg and a significant power loss yet it's octane rating is over 100.


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## PlasticMac (Apr 25, 2017)

What is the effect on the calorific value of the petrol we put in our tank, when ethanol is blended at 5 or 10%, compared to 0%?
Mac.


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## John949 (Apr 12, 2017)

> What is the effect on the calorific value of the petrol we put in our tank, when ethanol is blended at 5 or 10%, compared to 0%?


It's hard to be precise beause there is no mandated standard value for pump fuel. It can and does vary seasonally and with which hole in the ground it came out of, but we're probably talking less than 1% reduction. I'm sure Google will find some accurate data if you want to go into it in more detail.


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