E10 Fuel vs E5 Fuel | A science experiment – 44Teeth

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

1. Two samples of fuel will be procured. One will be standard premium unleaded E10, the other will be super unleaded E5.
2. 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).
3. Every component will be weighed and measured.
4. 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.
5. An identical selection of parts will be placed in each of the four samples. They will be left there for 60 days.
6. After 60 days, all the parts will be removed, measured and weighed.
7. 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

E5

E10V

E10

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.

Boothy