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Classic Engines, Modern Fuel

Comments on Topic: The Good, the Bad and the Ugly of E10

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Submitted by The Author

See the article published on this website:

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Submitted by The Author

In answer to your question. Alcohol and Ethanol are the same stuff. There are two differences between Cleveland Discol and E10.

Firstly the physical characteristics of ALL brands and grades of modern petrol are different from classic petrol. There is a whole chapter of the book that describes these differences. These are the cause of what many people refer to as the "hot restart problem". 

Secondly, although Discol contained ethanol, nobody I have spoke to knows at what concentration. It was probably less that 5% so that vehicles could use Discol and "normal" petrol without the need to be retuned. 

However, as you say, Discol did not appear to cause catastrophic failures in the 60's and 70's. 


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Submitted by Anonymous


Ethanol is an anti-knock additive. Removing it from the petrol reduces its RON and may make engines susceptible to pinking or knocking

1 ]     Given the content of your reply are you able to explain how and /or why Ethanol free petrol is freely available in the USA [see Attachment] and how / why the FBHVC openly advertise in their quarterly Newsletter that SUNOCO will / can supply Ethanol free fuel?

2  ]   The International Union of Pure and Applied Chemistry (IUPAC) seems to have brought Ethanol to the fore by re-naming Ethyl Alcohol . Is that so Ethanol is not confused with Tetra Ethyl Lead which is a component of the now defunct leaded fuel?

3 ]    If Ethanol is the same as Ethyl Alcohol, was there ever any evidence that Ethyl Alcohol damaged components in the way that Ethanol does?


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Submitted by The Author
  1. There are a number of additives that improve a petrol's knock resistance (i.e. increase its octane rating). The one we are most familiar with is the now obsolete Tetra Ethyl Lead. Ethanol also improves a petrol's knock resistance. Where fuel does not contain ethanol other chemicals are added. These include methyl tertiary-butyl ether (MTBE) and ferrocene. When a fuel contains ethanol this REPLACES the other anti-knock additives (although they still may be present at a lower concentration). Hence removing ethanol will reduce the octane rating of the fuel.
  2. One big advantage of using SUNOCO is that not only is it ethanol free, its volatility curve matches that of 1960's fuel. It addresses the Hot Restart Problem and does not "go off" like modern fuel. In addition classic engines run well on this fuel.
  3. Ethyl alchohol and Ethanol are the same substance (just a different name). Clevand Discol was introduced in 1928 and sold until 1968 this petrol contained ethanol and there is no evidence it caused damage to what are today's classic cars. However, it is not known what concentration of ethanol Discol contained.
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Submitted by James Cogan Ethanol Europe

Dear Paul,

I hope you are well.

I am an owner of a 1955 MG TF. I'm also spokesperson for a European ethanol manufacturing firm called Pannonia Bio (of which Ethanol Europe is part).

The Express on Sunday refers to your recent book and to E10 in dramatic terms... "could cause ‘burned pistons’ and valve damage".

I know your original piece on E10 is highly authoritative and also quite reassuring ("Older engines run better on ethanol blended petrol, reducing the expensive damage Cyclic Variability can cause. While there are some issues, they can be addressed with care and low cost solutions"), unlike the influential RAC for instance, which adopts the ultimately unhelpful "where no information is available assume the worst" approach, coming up with very large and wholly inaccurate numbers of vehicles which are not, under their advice, suited to E10.

The advice we give is simple and emphatic, and it is "all petrol engine vehicles, no matter the make, model or age, are suited to E10".

We base this advice on the very large volume of positive empirical evidence coming from the USA and the many other countries which have E10 or higher ethanol blend petrol as their only or main blend without any incidents ever having been reported. The US alone has over 250 million cars running on E10 exclusively for many years, and despite the litigious nature of the place, there's never been a claim against E10. The vintage car owners that I have contacted in the US don't even consider E10 to be a question mark. Every country that introduced E10 experienced some anxiety ahead of the transition, but then found there were no adverse impacts. More reading here:

What I wanted to ask you is, surely this empircal evidence represents compelling and comprehensive reassurance that E10 can be used in all petrol vehicles with peace of mind?

The UK seems set to subject itself to considerable and unnecessary anxiety and cost during the introduction of E10 by working on the basis that E10 isn't suited to all petrol vehicles, as drivers wonder which vehicles can and which cannot, or what to do if one inadvertently uses E10 or has no choice but to, or what the consequences might be for filling up with E10.

Congratulations on your book, and on your beautiful MG. We have had MGs at home since the 1950s.

Kind regards,


James Cogan

Ethanol Europe

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Submitted by The Author


Thanks for the kind comments about the book.

In my view by far the greatest danger to classic cars from E10 is SENSATIONAL JOURNALISM.

The article in the Express on Sunday ( is factually correct. Running an engine lean is very damaging. The point I made to the reporter was that this may be the reason some people view E10 as causing problems. While E5 has little effect on the carburettor settings, the tests at Manchester found E10 weakened the mixture to the extent the carburettor(s) required retuning.

As long as people are aware, it is a very simple problem to resolve, especially with variable jet carburettors. Unfortunately, in the Express on Sunday article, the way to address this problem is buried in the body of the text. Rather than up-front as it should have been.

The reporter also failed to mention the fact that we found the classic engine we tested at Manchester ran BETTER on ethanol blended fuels. The addition of ethanol probably REDUCES damage to a properly tuned engine by decreasing the level of cyclic variability.

As you can see from the article on E10 on this website, the greatest danger I found was due to water ingress, such as droplets of rainwater getting into the fuel tank. This danger is relevant to ALL ethanol blended fuels, not just E10. I have been contacted by motor cycle owners who have reported filters at the bottom of their petrol tanks have “dissolved”. Probably due to water ingress with the current ethanol blended fuels. Again, as long as you are aware, a relatively simple problem to address.

Unfortunately, while the few problems that E10 appeared to cause are relatively easy to address, I do not know how to address the scaremongering that is currently circulating in the media.

It it will help, please feel free to use the E10 article on this website and pictures as you see fit, providing you make reference to the book.


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Submitted by The Author

Dear Paul,

Thank you so much for your response. There has been much written on the subject but little enough systematic analysis and testing, as you have done.

On the lean running engine question I'll look again at the experience in the USA when they went to E10 all those years ago, as I'm curious to know how they addressed it. To date I have not come across information indicating that they did adjustments on a mass scale or that they encountered problems for not having done so.

On the water contact question it is reassuring that issues have not surfaced in the UK petrol vehicle fleet (18 million) running on E5 for the last decade, or indeed in the hundreds of millions of E5/E10/Ex fleets in the USA and elsewhere.

We will of course cite you and your book in any future public discussion of these matters.

Thank you again,


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Submitted by JJ

Dear Paul,

Ricardo Prado in Brazil posted the following comments on my website following publication of your E10 article:

"Dear Sirs, Compliments for keeping quality information as usual. I read the E10 article, and would like to share with you that in my country, Brazil, since long ago the petrol has 25% of alcohol mixed. Even with original cars, with original engine not rebuilt, apparently very small change observed in terms of maintenance and performance. For SU carbs I never experience corrosion (I own my TC 41 yrs. now) but it is necessary to change the carb needle to enrich slightly the mixture. The only detail is keeping the first 2 zones of the needle very near or same as original to be easier to adjust idle. I suspect also that in TC it becomes more prone to vapour lock, so I added a heat shield to solve this issue. For cars with Solex carbs, I use to enlarge the main gicleur about 10% in diameter. Never had problem with valve seats or other. Important to say that here also, the gas only lasts about 3 months. After this period, a kind of brown mud can forms and block carb holes and sometimes seize valves or even pistons. Best regards,"

JOHN JAMES Editoe, ;Totally T-Type 2'.

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Submitted by JohnT

I just found this thread, so my comments may be somewhat out of date, but being from the USA, I can provide some perspective. No wholesale retuning of cars was done with the switch to E10. The computer-controlled fuel injection cars, of course, self adust by using oxygen sensors. All the carburetted cars allow some adjustment, although the fixed-venturi carburators have a narrower range of adjustment and, in their later years, that range was limited by regulation. A bigger concern was the reduction in octane rating from ~100 to 91 - 93 (MON+RON/2, as is standard in the USA). The late 1960's and early 1970's muscle cars required retarding the ignition setting. Those of us with variable-venturi SUs and such would either retune them or exchange the standard needles for rich needles. Since British car owners tend to be fiddling with their SUs anyway, not much effort was involved.

Ethanol-free fuel is available in some states (California is not one of them) and some owners will seek it out, believing it is better for their cars. When I've been on a trip with one of those owners, they didn't retune the Austin-Healey when using the ethanol-free fuel.

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Submitted by mangocrazy


Having read through this thread and owning both classic cars and motorcycles, I would make the point that potential damage from ethanol is more likely to occur in the storage and delivery phases than when the fuel is being burnt in the engine. Old fuel hoses are an obvious weak point, but damage to petrol tanks is definitely the Ugly side of Ethanol (be it E5 or E10). If you have a steel fuel tank, it will rust internally when you use ethanol - there are no ifs or buts about that. There are in-tank aftermarket treatments that can be employed to mitigate this problem, but if the tank is left untreated then rust and consequent perforation of the tank is an inevitable consequence. The only variable is how long it will take.

Motorcycles have for many years used plastic tanks (of various formulations). Almost without exception owners of plastic fuel tanks fitted to many different manufacturer's bikes have experienced problems. These problems range from swelling of the fuel tank such that it no longer fits to its mounting points, blistering leading to eventual leakage and subsequent scrappage and warping around the fuel filler cap leading to potentially dangerous escape of fuel. So it is clearly inaccurate and verging on the reckless to say that all vehicles can safely use E10. They cannot, at least not without major and expensive modifications.

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Submitted by The Author


I agree with your comments about the storage issues with ethanol blended petrol. However, I think there are two problems with the publicity in the press:

  1. The UK Government has lablelled E5 Super Grades as "protection-grade". As you say, it is just as dangerous as E10.
  2. There has been a great deal of "scarmongry" about the effects of ethanol. Yes it does cause problems with hoses and petrol tanks - but it is here to stay. In my view, it is more important that classic motor bike and car owners are aware of the problems rather than panic and do not use thier classic vehicles. This is the point I was trying to make in the book.

I disagree with your comment about expensive modifications - providing early steps are taken to mittigate the problems. For example, replacing fuel hoses, slosh coating petrol tanks are cheap solutions. If you are planning to store your classic vehicle for some time or are a low milage user, you can use an ethnol free fuel such as R-Storage Plus.

As I said, I think the most important message is that owners need to be aware of the problems and take steps to address them before the become too serious.

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Submitted by Rick

Couple of things

If you don't have this excellent publication that Paul has done, get it!

If James Cogan has opinions then they should be based on his companies testing and research and publish pier reviews not what's anecdotally happening in the world because we all know bias, taking positives, leaving negatives and adding to misinformation can skew what should be science.

There is just as much evidence against in the US, EU and Australia. As an example I read on my Honda outdoor power equipment manual to never use e10 in any of their equipment. I've seen the ethanol fall out of suspension and sludge up the outlet in fuel tanks (a number of them) that have been stored for several months and I can go on with what I have observed, so it's not Al beer and skittles.

If you want to know if the fuel you've purchased has ethanol or methanol in it, sample some in a bottle (preferably glass), add some water (just a little) and shake, see the result. No ethanol or methanol when everything settles you'll see the water as water in the bottom (water is heavier). If it's white and a little thicker and sludging around the bottom (so the alcohol falls out of suspension readily) you'll know what you have.


And yes water in the tank is not good either but I'm just showing a quick way of identifying it. There is no way of gauging the amount using this process.

Please wait .....