Will A Lawnmower Run On E10 Fuel?

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There has been a recent shift from E5 to E10 as the new standard unleaded petrol in the UK. It is a measure to reduce carbon emissions from cars and other forms of transportation. This results in all filling stations selling unleaded E10 petrol with 10% renewable ethanol.

So, will a lawnmower run on E10 ?

A lawnmower will run initially on E10 fuel, however, it will eventually lead to starting issues and damage to the engine including rubber gaskets, seals, plastic components, and incorrect engine lubrication when it mixes with oil. It is always best to use regular unleaded fuel (ULP) whenever possible.

E5 contains 5% renewable ethanol and E10 contains 10% bioethanol.

The shift has triggered many concerns about how E10 will interact with the small engines in garden equipment in particular lawnmowers.

The ethanol is produced by fermenting grains or plants like corn, sugarcane, and their byproducts.

When you turn plants into biofuel (bioethanol, in this case), they absorb more atmospheric CO2 than they release during the process of production and combustion. This yields an alcohol-based fuel that is atmospherically carbon-neutral compared to regular petrol (ULP).

The Department of Transport claims the shift to E10 petrol will decrease the UK’s CO2 emissions by 750,000 tones or 2% per year.

Environmentalists are psyched about the reduction of emissions. But what about lawnmowers?

While there is ample information about how E10 will impact cars, there are unanswered questions about E10 and lawnmowers. I will answer some of the commonly asked questions about ethanol blends and garden gear in this post.

Will my lawnmower run on E10 petrol

Lawnmowers generally run on unleaded petrol with a minimum of 87 octanes (RON).

They can run on ethanol-blends that have 10% or lesser ethanol. The owner must check if the lawnmower or garden machinery is E10 compatible.

You can run a lawnmower on E10 petrol if it is compatible.

  • John Deere, Briggs & Stratton, Hayter, and others have released a list of models compatible with E10. Some manufacturers are yet to give clear-cut guidelines.

For example, Honda lawnmowers are E10 compatible, but Honda updated the Lawn Mower Fuel Recommendations on their website.

  • Honda caution against using petrol with more than 10% ethanol as it is corrosive and “can cause starting or running problems” in the fuel system.

This question crops up because Ethanol attracts water and absorbs moisture from the atmosphere.

  • Water creates trouble in the fuel system, mainly problems starting the lawnmower or corrosion in the fuel system components.

Most experts suggest it is best to pay extra and use regular unleaded fuel to run your lawnmower, even if it costs more. There could be some long-term damage to metal and plastic components if you use E10 to run a lawnmower.

Gas or petrol lawnmowers have been prone to starting issues over the years, so don’t jump to conclusions as you drag your mower out of the shed for the first time in months.

Take a look at this awesome YouTube video that shows why lawnmowers won’t start and be sure to check these simple things first.

Why you should not use ethanol petrol (E10/E5) for lawnmowers?

Cars have larger engines. Plus, we use them frequently, if not daily. Garden gear has small engines.

  • Small engines more susceptible to deterioration because they sit around with fuel in the tank when not in use (or during the off-season).

Ethanol is hygroscopic – it attracts moisture from the air. If E10 fuel is in a fuel tank, it absorbs moisture and creates water that enters the fuel system. This combination of water and ethanol degrades components or causes cold starting and running problems.

Additionally, the water mixes with oil and prevents proper lubrication of metal components. The components begin to rust or deteriorate over time.

The biggest concern is leaving E10 petrol in the fuel tank for long periods during wet/cold weather.

But on the whole, E10 can potentially cause multiple problems for lawnmower engines.

How to check if your lawnmower compatible with E10

The UK government recommends checking the product manuals for compatibility guidelines before using E10.

Do not use E10 if your lawnmower is not certified to run on it. It may damage the plastic, metal, fiberglass, and rubber components of the fuel system. Use regular unleaded fuel (ULP) to be safe and avoid any problems. 

Secondly, just because your lawnmower is E10 compatible’ does not mean that it is safe to use without additional care.

You should avoid using stale fuel and keeping fuel in the tank for long periods. Most people are unaware that petrol can be out of date, but petrol has a shelf life.

You can read about the shelf life of E10 and 91 petrol for more information on the subject. You may need to take a few precautions to store petrol and look for an appropriate fuel stabilizer or additive to prevent corrosion in the lawnmower engine.

How long does E10 petrol work/last for in a lawnmower?

The food industry replaced sugarcane sweeteners in food with a substitute made from corn starch. Adding ethanol to petrol was an extension of the same principle. It was done to dilute petrol, reduce costs, and lower CO2 emissions while stretching out the supply.

But is it as efficient, and how long does it last in a lawnmower?

  • Ethanol is considered fresh for 60 to 90 days. It has a shelf life of 3 months as per the US Energy Information Administration. So, if it is sitting for too long in your garage, it is considered stale fuel that is unfit to use in your mower. That’s if it was stored properly in a sealed container.

You can lengthen the life of E10 and improve efficiency with fuel stabilizers but it will add to the cost.

Furthermore, ethanol is easy to blend with petrol but less energy dense.

In cars, studies have shown that E10 fuel reduces miles per gallon by 1% to 3%. The same decrease in efficiency should be expected in other use cases such as using E10 to run garden gear.

Take a look at this video that shows the rubber gaskets inside a Briggs and Stratton Lawnmower

Does E10 petrol in a lawnmower need any additives?

You should add additives if you use E10 petrol in a lawnmower.

Any fuel blend that contains ethanol can damage the lawnmower engine. Fuel additives do not remove ethanol from fuel but they protect the components of the fuel system and engine from the ill-effects of ethanol.

In a recent release, Briggs and Stratton announced that their overhead-valve and side-valve engines are compatible with E10 petrol. This may be all well and good for the engine block itself but not for the carburetor components or intake and head gaskets.

However, they recommend Fuel Fit (fuel stabilizer) with a 25% increased dosage if you use up to 10% ethanol petrol. You can also use B3C Ethanol Shield Fuel Stabilizer, B3C Ethanol Shield 2-Stroke Oil, Hayter Premium Fuel Stabilizer Treatment, and other corrosion inhibitors recommended by the manufacturer.

Fuel additives have three-pronged action. They contain corrosion inhibitors that form a protective coating over the metal components of the fuel system.

Secondly, they have metal de-activators to prevent adverse chemical reactions caused by metals in the fuel. Lastly, they have ingredients that prevent varnish build-up in the engine.

Again, wherever possible use regular unleaded fuel.

Why is E10 fuel bad for lawn mowers

Some lawnmowers are not compatible with E10 fuel. Among those that are, E10 can still cause damage if you keep fuel in the tank through the winter months.

Ethanol blends degrade/corrode plastic and metal components in the lawnmower engines over time. Plus, it is far from ideal to use E10 if your lawnmower is idle for weeks at a time.

  • E10 petrol is likely to damage anything that is not made from suitable rubber.

The rubber diaphragms in the carburetor, for instance, can develop pinholes and bubbles over time. Additionally, ethanol can block capillaries in the carburetor, which can lead to serious engine issues.

No matter what you choose, don’t store E10 petrol when it is not in use for weeks at a time.

Drain the tank and add the petrol to your car if it is E10 compatible. Or else, get rid of the petrol safely after the mowing season and start with a fresh refill in spring.

Many people are now switching to battery-powered lawnmowers, Batteries are becoming more powerful and longer-lasting each year, and don’t have the problem of dragging an electric wire along behind you or using petrol, (or having a rope to pull start!)

Can you mix E5 and E10 petrol in a lawnmower?

You can mix E5 and E10 petrol safely.

In guidance issued by the Department of Transport, UK, it is stated that E5 and E10 are compatible.

It is similar to mixing any two grades of petrol or mixing super unleaded and regular petrol in the same tank.

That said, ethanol blends of petrol cause serious issues when used in small petrol engines – the kinds you have in your lawnmower.

Therefore, you should avoid using either E5, E10, or a mix in any non-compatible garden equipment. Opt for super unleaded petrol unless the manufacturer of your model has clearly stated it is safe to use E10 to run your lawnmower.

Here’s another great video that covers general starting issues on various styles of petrol lawnmowers.

In Conclusion

Here, a final recap of the key points we discussed in this article:

  • Contact the lawnmower dealer or manufacturer to check E10 compatibility.
  • Don’t leave E10 in the fuel tank during cold or wet weather.
  • Don’t keep the lawnmower idle for days/weeks with a full tank.
  • Use a fuel stabilizer if it takes more than 90 days to consume E10 petrol in a lawnmower.
  • When in doubt, avoid E10 and user super unleaded petrol.

I hope makes up for the dearth of information about the safety issues and precautions that need to be taken for lawnmowers and garden gear.

Whether you use super unleaded, E5 or E10, don’t forget to seal off the vent or drain the fuel tank when you put away your lawnmower for winter.

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