Can I Use E10 Petrol In My Lawn Mower? The E5 – E10 Change Over

The ongoing concerns with the change from E5 to E10 is currently being debated all over social media. Will E10 cause harm to your equipment, the short answer is.. It depends. This prompted me to do some research and find out exactly what’s going on so that I could share the information.
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What is E10 Fuel?
In short E10 is a greener blend of petrol than the Pre September 2021 standard E5 fuel has been used in Britain for many years. It contains a higher percentage of bioethanol (which is a renewable fuel), than the current E5 mix, which means lower carbon emissions and lower impact on the planet. The ethanol is produced by fermenting plants such as wheat, corn and sugar beets into alcohol then added to the petrol before it leaves the plant.
In theory E10 is slightly cheaper than regular unleaded due to the higher ethanol levels and your mower may well run on it without any immediate problems, but long term this will be a different story. Ethanol has a liking for water and, when E10 fuel is left in the fuel tank or stored in a fuel can for extended periods of time, especially over the wetter and colder winter months. Of course this will have more of an impact on those that store machinery in unheated areas outside. Ethanol can readily absorb moisture from the atmosphere, meaning any contact with air will result in some form of absorption. This moisture can corrode parts of your fuel system, which poses a potential safety risk as well as reducing the lifespan of your machinery.
That’s not all, the ethanol can actually dissolve in the water and create an ethanol-water mix that will then separate from the petrol, forming two distinct layers. These layers will cause you a few headaches in the spring when starting the machinery for the first time. This is one of the main reasons why the shelf life for oil fuels is usually around 3 months.
Water getting into any engine is always bad news, and can be very expensive to repair.
Fuel Storage
Even if your machinery is compatible with E10 you should air on the side of caution. Especially if you leave machinery for over 30 days with E10 in. For these situations the likes of Honda recommend adding a petrol stabilizer to the fuel tank and filling the tank to the brim, as the aforementioned air in the tank will “promote fuel deterioration during storage”. Stabilizers can stop fuel degrading for upto 24 weeks depending on the brand and type.
Mowers Online also recommends a fuel stabilizer, as “ethanol causes multiple problems for small petrol engines and you shouldn’t leave it in the tank”.
AA technical specialist, Greg Carter, warned against using E10 in lawn mowers and recommended only buying the ‘super unleaded’ for garden equipment. As super unleaded will remain E5 for some time. Eliminating the issue entirely, although more expensive!
How can I tell if my machinery is compatible with E10?
One of the easiest ways is to simply contact the manufacturer, alternatively you can check the manual. Compatibility is pretty much based on the effectiveness of the fuel systems to keep moisture out, since this is the main cause of issues. Chances are if the machine was built before 2021 it won’t be compatible. But this doesn’t mean that any machine built after 2021 is compatible either, old stock or machines that haven’t been updated will still be incompatible. Honda have made the document in the link below stating as long as the fuel doesn’t go over it’s shelf life E10 is safe to use in their engines.
Honda Engines | Fuel Recommendations
Here’s some more links you may find useful when searching to see if your machine is E10 compatible. I recommend getting the full go ahead from your manufacturer before deciding to take the switch.

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