What’s the deal with E10 fuel? We enlist an expert to answer your 'green petrol' questions

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From September 2021 ‘E10’ will become the new standard unleaded petrol in UK filling stations and the changeover has sparked concerns that it could cause poor running or even damage on some bikes. 

Are these worries valid? We’ve checked with the experts to see if E10 is really likely to cause problems, and what you can do to prevent them. 

What is E10 and why is it being introduced?

At the moment, normal unleaded (confusingly called ‘Premium Unleaded’ despite being the standard stuff) is ‘E5’, which means it has no more than 5% ethanol content. Ethanol is simply alcohol, and normally comes from renewable sources so it’s ‘green’ compared to petrol from oil wells. As its name suggests, E10 has a higher ethanol content of up to 10%.

Jamie Baker, Director of External Relations at the UK Petroleum Industry Association, said: “In the UK, E10 will be petrol containing at least 5.5% and up to 10% ethanol – with the remainder made up principally of hydrocarbons. Currently, standard (premium) petrol contains up to 5% ethanol.”

“As almost all ethanol blended into petrol in the UK is renewable in origin – known as bioethanol – the fuel manufacturing greenhouse gas emissions – known as ‘well-to-tank’ emissions – are significantly lower than fossil-derived petrol. Therefore, increasing the bioethanol content of petrol will reduce the greenhouse gas emissions of the UK’s petrol and overall UK petrol vehicle carbon emissions.”

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Will E10 damage my motorbike?

There’s no shortage of scare stories about high-ethanol fuel, often based in an element of truth but blown out of all proportion. 

The fears about ethanol stem from a couple of its properties. One is that pure ethanol, being alcohol, is hygroscopic – it attracts water, even pulling it out of the air around it – unlike petrol, which separates from water.

In the right circumstances, the concern is that ethanol absorbs enough water to cause ‘phase separation’, where the ethanol/water mixture separates from the petrol and sinks to the bottom of the tank. In reality, though, this isn’t a huge concern, as even in very humid environments phase separation doesn’t usually happen before the petrol itself has gone stale.

Another concern over the long term is that ethanol can become acidic, speeding up corrosion of some materials, but again this is only going to happen if the fuel is left in the tank for long periods of time.

Ethanol is also a solvent, so can attack some gaskets or seals on older bikes that weren’t designed with it in mind. It also damages resins used in fibreglass, so E10 shouldn’t be used with fibreglass fuel tanks, although these are rare (many modern bikes use plastic tanks, but these aren’t the same as fibreglass). 

Baker said: “As long as your bike is compatible with up to 10% ethanol petrol, you can use it as you would the incumbent E5 petrol.”

When it comes to actually burning E10, modern bikes will accept it without a concern, as they have O2 sensors in the exhausts that automatically tell the injection to recalibrate for the best combustion. On older bikes with carbs or early injection systems, E10 can cause lean running although this can easily be tuned out.

If I need to use more throttle to get the same performance from E10, does this outweigh the environmental benefit?

Ethanol is actually higher-octane than petrol (pure ethanol is 108-RON), which means it actually helps keep combustion temperatures down and give a more controllable burn, but it is less energy-dense than pure petrol.

The difference is pretty small (ethanol contains 33.18 megajoules per litre, petrol has 34.2 MJ/L), so a 5% increase in ethanol makes for a very small change in efficiency.

The AA suggests fuel economy could be reduced by 1%, and Baker told us: “Any increases in consumption of fuel due to the differences in energy density between E5 and E10 petrol are outweighed by the reduction in well-to-tank greenhouse emissions by increasing the bioethanol content of petrol.”

Filling a Kawasaki with petrol

Can I leave E10 in my tank while my bike is stored?

Concerns over storing E10 are rife, but the truth is that petrol itself doesn’t really like being stored for the long term. BP says that its storage life is one year in a sealed container, dropping to six months once that seal is broken at 20°C or three months if stored above 30°C.

Even after just a few weeks, evaporation means that the fuel in your tank becomes denser (as the lighter components of petrol are the first to evaporate), which means the air/fuel ration in you engine will be richer when you start it. 

As mentioned above, phase separation can also occur (where the ethanol absorbs water and separates) over long-term storage, but again this will only be one of your problems if fuel is left in a tank for that long.

If you’re concerned, it might be an idea to use ‘Super’ unleaded, with less than 5% ethanol, for your last tankful before putting your bike away for winter. But Jamie Baker says: “As long as your bike is compatible with up to 10% ethanol petrol, you should not notice any difference in the long-term storage stability of E10 compared to the incumbent E5 petrol.”

Should I use fuel additives?

Jamie Baker of the UKPIA says: “The use of aftermarket additives is not recommended and should only be considered with advice from your motorcycle manufacturer. Most petrol products already contain additives for product operability with some containing additives for performance purposes such as detergents for component cleanliness.”

Have European riders had any problems using E10?

Baker says: “The vast majority of riders in European countries that have introduced E10 petrol have been able to use it without any issues. There may be some models that cannot use E10, such as historic motorcycles that utilise fibreglass tanks.”

It’s also worth bearing in mind that E10 has been the norm in the USA for several years, with higher ethanol blends including E15 and E85 also on offer over there, so most bikes are created to cope with it.

How can I tell if my bike is compatible with E10?

All bikes made since 2011 are compatible with E10 however for many manufacturers their compatibility stretches much further back.

Honda for instance say all bikes made since 1993 are safe, Harley-Davidson say all bikes made since 1980 are fine while BMW say every bike they’ve ever made will be alright as long as you get the correct octane. If you’re not sure, you can check on the Government’s website.

If you’re still not sure, check with your bike’s manufacturer or take the simplest option of all and use E5 Super Unleaded, which has been guaranteed to remain on sale all over the country after the adoption of ‘Premium’ E10. All pumps will be marked with either ‘E10’ or ‘E5’ logos to make it clear which one you’re putting in.

If you accidentally fill up with E10, don’t worry too much even if your bike isn’t officially compatible with it. The potential problems take time to emerge, so just make sure you refill with E5 when you’re next at the pumps.

Fuels rush in: Will my motorbike run on E10 fuel?

First published on 26 March, 2020 by Ben Clarke

Filling up with E5 petrol

The Government has taken the decision to introduce E10 as the standard 95-grade petrol by September 2021. E10 petrol has a higher content of ethanol (10%) compared to E5 (5%), which is our current standard.

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The Government has calculated that vehicles using E10 fuel emit approximately 2% less CO2 than those running on E5, which will have the equivalent effect of removing 350,000 cars from the road. The UK is arguably lagging behind with the introduction of E10 fuel, with most of Europe, and indeed much of the world, using E10 as standard in their pumps.

But there can be unwanted side effects when using fuel with a higher ethanol content, especially for those with older bikes. Ethanol can damage plastic or fibreglass fuel tanks, cause old rubber hoses or inlet manifolds to swell or split and react with zinc, lead and aluminium components, too.

Ethanol is also hygroscopic, meaning that it absorbs moisture from the air around it, and this can cause problems when fuel is left to rest in tanks for long periods.

Is it safe to use E10 fuel in my motorcycle?

If you ride an older bike this may cause issues, but most modern machines are perfectly capable of running on E10. The fuel is already sold in many European countries including Germany, France, Belgium and Spain, in fact.

The first thing you should check is your fuel tank itself. You may find there’s a sticker you’ve never noticed before with an E5 and E10 logo, indicating that your bike is compatible with either fuel.

If you are still unsure about your bike, you can use the Government checker, although not all bike manufacturers have provided the necessary information.


E10 compatibility stickers

If you do not have the sticker, consult your owner’s manual or, failing that, contact your dealer. MCN spoke to major bike brands back in 2013 when E10 was first introduced to find out what a switch to higher ethanol fuel would mean for them.

The least-affected brands were Yamaha, Triumph, Honda and BMW. Yamaha and Triumph both said that all models from 1990-on are compatible with E10, while Honda said everything post-1993 is compatible, although carburettor-equipped models could experience poor driveability in cold weather.

BMW said that all their models regardless of the year of manufacture can run on E10 fuel with no adverse effects.

Suzuki models made after 2002 are compatible with E10 and those made after 1992 might be but owners should seek advice.

Ducati said that their Multistrada 620 and 1000 models were not compatible with E10 fuel, with tanks known to expand or leak in markets with ethanol-rich fuel.

And Kawasaki said that models made from 2006-on would be ok on E10 but advised customers not to use the fuel in bikes that weren’t specifically approved.

Piaggio (who own Moto Guzzi and Aprilia) were the least E10-friendly manufacturer in 2012, saying that all motorbikes built before 2011 would not be compatible with the fuel.

The history of E10 fuel in the UK

UK fuel stations have been legally entitled to supply E10 fuel since 2012 but none have opted to do so. This is because none of the retailers want to be the first to supply E10 in case it means customers opt to refuel elsewhere.

And the chances are, they would. Ethanol is less energy dense than petrol, so fuel with a higher ethanol content is slightly less efficient, hitting customers’ wallets as well as engine performance. E10 fuel will also cost more than the E5 we use now. If approved, the changes would come into effect in 2021.

Ben Purvis

By Ben Purvis