Last year the UK government decided that ‘standard’ premium unleaded petrol would go from being E5 to E10; that’s to say it would have an ethanol content of 10%, rather than the previous 5%. The expectation is that it should cut CO2 emissions by 700,000 tonnes. At the same time though, it has the potential to damage the fuel systems in thousands of older road vehicles; cars, bikes, the lot. In short, it’s because ethanol’s quite an aggressive solvent, so the higher ethanol content in E10 fuel can, if left, dissolve materials. Things like rubber hoses, o-rings, plastic parts and certain soft metals. Or that’s what we’re lead to believe.
Because, of course, you can still purchase the lower content E5 petrol, in the form of the higher octane ‘super unleaded’. But of course that’s usually a good 10% more expensive.
But do we really need to? Does the extra 50ml of ethanol per litre of fuel really make a difference? Or is it just scare tactics from the government and the petrochemical industry who both stand to gain massive amounts of revenue when everyone with a 20 year old + car switches to the more expensive super unleaded fuel?
I’m keen to find out, so I’m going to conduct my own little experiment.
Hypothesis
My hypothesis is that although chemically, E10 fuel has the potential to be more harmful to a range of materials, in practice the difference between E5 and E10 won’t be great enough to cause any significant effect to anything that it might come into contact with, in its application.
And that the government and the petrochemical industry are dead keen E5 ‘super unleaded’ is used in older vehicles, firstly because of the massive financial benefit to them, and secondly because they are desperate to avoid any possible legal ramifications, on the microscopically slim off-chance that E10 does cause lasting damage to anyone’s vehicles.
That’s what I think at the moment and I know it’s not a particularly popular view, so that’s why I’ve designed this experiment to try and find out the truth.
Scientific Method
- Two samples of fuel will be procured. One will be standard premium unleaded E10, the other will be super unleaded E5.
- A selection of materials (which one would expect fuel to come into contact with) will be sourced. The following materials will be used; rubber (o-ring and fuel pipe), plastic (tie wrap), aluminium (wire), steel (washer), brass (infector).
- Every component will be weighed and measured.
- The E10 fuel will be split into two samples and the E5 fuel will be split into two samples. Both the E5 and the E10 will have a vented and a non-vented sample.
- An identical selection of parts will be placed in each of the four samples. They will be left there for 60 days.
- After 60 days, all the parts will be removed, measured and weighed.
- The weights and measurements will be compared with those of the corresponding parts at the beginning of the experiment, to determine whether or not any of the fuel samples had any effect on the components, and if they did, whether the E10 sample had a greater effect than the E5 sample.
Results
E5V
| Component | Original Weight (g) | Original thickness (mm) | Post experiment weight (g) | Post-experiment thickness (mm) |
| Rubber hose | 5 | 13.3 | 6 | 13.2 |
| Plastic Tie wrap | 0 | 1.1 | 0 | 1.2 |
| Steel washer | 3 | 1.0 | 2 | 1.0 |
| Brass | 14 | 6.3 | 14 | 6.3 |
| Rubber O-ring | 0 | 3.0 | 0 | 3.2 |
| Aluminium wire | 0 | 2.3 | 0 | 2.3 |
E5
| Component | Original Weight (g) | Original thickness (mm) | Post experiment weight (g) | Post-experiment thickness (mm) |
| Rubber hose | 6 | 13.1 | 7 | 13.1 |
| Plastic Tie wrap | 0 | 1.1 | 0 | 1.2 |
| Steel washer | 3 | 1.0 | 3 | 1.0 |
| Brass | 14 | 6.3 | 13 | 6.3 |
| Rubber O-ring | 0 | 2.9 | 0 | 3.0 |
| Aluminium wire | 0 | 2.3 | 0 | 2.3 |
E10V
| Component | Original Weight (g) | Original thickness (mm) | Post experiment weight (g) | Post-experiment thickness (mm) |
| Rubber hose | 6 | 12.6 | 7 | 14.1 |
| Plastic Tie wrap | 0 | 1.1 | 0 | 1.8 |
| Steel washer | 3 | 1.0 | 3 | 1.0 |
| Brass | 14 | 6.3 | 15 | 6.3 |
| Rubber O-ring | 0 | 3.1 | 0 | 3.4 |
| Aluminium wire | 0 | 2.3 | 0 | 2.3 |
E10
| Component | Original Weight (g) | Original thickness (mm) | Post experiment weight (g) | Post-experiment thickness (mm) |
| Rubber hose | 7 | 13.5 | 8 | 13.5 |
| Plastic Tie wrap | 0 | 1.0 | 0 | 1.2 |
| Steel washer | 2 | 1.1 | 2 | 1.0 |
| Brass | 14 | 6.3 | 14 | 6.3 |
| Rubber O-ring | 0 | 3.0 | 0 | 3.4 |
| Aluminium wire | 0 | 2.3 | 0 | 2.3 |
Conclusions
I was wrong. It turns out, according to my experiment, there is a difference in the way components of certain materials react to E5 fuel compared to E10 fuel. That said, the only material that showed any real signs of effect from the fuel was rubber, specifically the rubber O-ring.
Across the board, there were a number of slight differences between the weights and measurements of the components before and after being submerged in the various fuel samples for 60 days, however if we allow a measuring accuracy tolerance of 1g and 0.2mm, almost all of these differences are negligible. Apart from in the case of the rubber O-ring.
After being submerged in the E10 (non -vented) fuel for 60 days, the rubber O-ring was 0.4mm thicker than it had been before. That’s a fairly significant growth. Particularly when you consider the fact that a rubber O-ring is a type of seal almost always used somewhere in fuel systems, old and new.
Should you be using an O-ring made out of rubber which is not resistant to the extra ethanol content in E10 fuel, you might come unstuck. Because if E10 has that effect on that particular rubber after two months, imagine how much of an effect it could have on it after two years.
Recommendations
So if you’re wondering whether or not it’s worth risking sticking E10 fuel into your classic bike, I really would think long and hard about it. If you want my advice, for the extra quid or two it’s going to cost you to fill the tank up, I think it’s definitely worth opting for the higher octane, lower ethanol content, super-unleaded option.
I might have been slightly sceptical about it before, and I’m still not 100% convinced exactly how much transitioning to E10 fuel is going to help save the planet. But now, after conducting my little experiment, I am convinced that it can (and probably will) cause problems to your fuel system, if it hasn’t been made with the latest, up-to-date materials.
So use E10 fuel at your own peril.
8 Responses
For the extra cost (and extra performance) since E10 all I ever use is 99 ron. I’ve seen and read too much about E10 to not be a believer.
Here in the Midwest, we’ve been cursed with E10 for ages. With modern vehicles, you won’t really have any problems, but older stuff can have issues.
The real problem I’ve seen is how quickly E10 goes bad. If you have a carbureted engine, you’re at extreme risk of a gummed up mess. The only thing you can do is to religiously use a fuel stabilizer. Even with my modern bikes, if I think it will sit for more than 2 weeks, it gets a good dose of stabilizer.
Occasionally in my travels I’ll find E0, and when I do, I buy it. Seems like the most common places are near lakes (for boats) and up north (for snowmobiles).
I’d be interested on how the extra 5% ethanol affects the octane or knock properties in e10 to e5. I know the e10 produces less power and calorific energy so less milage too. But not read anything on its ability to suppress knock
I don’t know that E10 has enough anti-knock properties to really make a difference. But there’s a trend here of certain turbo/supercharged cars having aftermarket tunes optimized for E85 since that’s definitely got some anti-knock goodness.
Unfortunately, the half-life of E10 is much worse.
After three months, the fuel becomes thick and the ignition effect diminishes considerably and nozzles clog.
E10 should not be left in the tank without a preservative (just look for Liquid Moly).
The other important point with the rubber the test did not address is if the e10 makes them less elastic and more brittle
Also the E10 contains less energy so you will travel less distance on a gallon. My Citroen c1 is averaging 56 per gallon now on E10 previously it was averaging 61 per gallon. My Honda Forza 125 is down from 114 per gallon to 106. And it has started to run a bit tough, I am now running it on E5 to see if it will run like it used to.
I simply want to know.
What is green saving one litre E5 v E10 – lots of carbon in making ethanol etc. We do not save 5% e5 to e10. To follow let’s say 2%. of 5% etc. But loss of mpg may be 2% of 100%? E10 is dirtier than ever FULLSTOP! I spoofed BMW Park Lane in 1979 into agreeing to supply two 700s for alcohol fuel to Nelson Piquet’s brother – honest. E10 is brilliant for USA to subsidise USA farmers to raise world food prices for the poor and screw your good willed motorist and mechanics.
Apart from HS2, E10 is the worst ever economic decision since James Watt 1776. Good old capitalism – feed the rich and starve the poor, capitalism is brill if it is fairly controlled.
Get a proper evaluation e10 v e5 and then by threatening a general strike tell the greatest bleeder of all to take e10 off our pumps. Where is the elusive free trade at encourages oil companies to gouge 20p extra for e5, last year it was 4p. Prematurey scrapped cars is very aggressive to green?
I am not suggesting revolution when rebellion will do. I own 3 x 20 yo Jaguars, and nothing newer and at 5000m/year spend hoots more money employing mechanics and part suppliers than I do on fuel, especially the 5% that feeds the rich and robs the poor