What is E10?

E10 fuel is essentially petrol, or rather a blend of petrol that has now become widely available for sale from forecourts across the United Kingdom. The letter ‘E’ stands for Ethanol. Ethanol is a form of alcohol and has been produced by fermenting grains and plants to turn the naturally occurring sugars into high concentration alcohol. The number ‘10’ refers to the percentage of the mix of ethanol. In this instance, E10 is made up of 90% petroleum and additives and 10% ethanol alcohol. Up until recently, the standard has been ‘E5’ or 95% petroleum and 5% ethanol.

Why make the change?

The reason for the move to E10 is environmentally driven. In theory, ethanol is carbon neutral. Because it is produced from plants, which absorb carbon from the atmosphere as they grow, the burning of the fuel should only release that same amount of carbon that was originally absorbed from the air.

Sounds great, so why aren’t all engines using pure ethanol fuel?

It’s complicated, but to put it in simple terms, ethanol contains around 30% less energy than petrol – it just can’t deliver the same amount of bang when ignited.

So, what is the controversy with ethanol in petrol?

The recent change to E10 has reignited the debate regarding the use of ethanol in fuel. Unlike petrol, ethanol is water soluble and can ‘attract’ water from the atmosphere if not properly managed during the production, storage and distribution process. Water in petrol is not good for the performance of an engine. Water and petrol don’t mix, so if it becomes present in your fuel tank, the ethanol/water mix can separate from the petrol forming two distinct layers. What’s more, it can also attract contaminants that collect in fuel filters, carburettors and injectors. In small engines that are infrequently used, this could theoretically lead to problems as fuel left for long periods of time could collect more water from the atmosphere while it sits around waiting to be used.

Engines that have not been designed for higher ethanol blends could have components made with materials that are not 100% compatible for use with such fuels. On older machinery, components such as seals and hoses could experience faster degradation with E10 than they would running on regular unleaded petrol.

Can my tractor run on E10 petrol without problems?

There is unfortunately not one answer to this question as it depends upon the age and model of your tractor and also how the tractor is used, maintained and stored. However, here are the headlines that should give you a good indication.

Modern twin-cylinder Countax or Westwood tractors:

If your Countax or Westwood has a twin cylinder engine and is around 12 years old or less or is a current production model, it is almost certainly fitted with a Kawasaki engine. The good news here is that Kawasaki confirm that their engines will run on E10 fuel with a minimum octane of 91 RON. Most petrol-station unleaded will typically be 95 RON octane and therefore okay to use. However, Kawasaki are keen to highlight that fuel does have a shelf life. If you store the petrol in your fuel tank over winter you could still have a problem.

Modern single-cylinder Countax or Westwood tractors:

Ariens engines are also approved for use with E10 fuel as long as it is over 90 RON. Again, with most forecourt petrol rated at 95 RON, users should not expect any issues

Older Countax and Westwood tractors:

Depending upon the engine you have fitted to your tractor, the advice from the manufacturer differs. If you don’t know or can’t remember the engine manufacturer of your tractor, consult your operator’s manual or lift up the bonnet and check. All of the manufacturers place a brand decal on the top of the engine close to the air inlet.

Here is a summary of advice that should cover most models:

Briggs and Stratton

Briggs and Stratton confirm that their engines are indeed compatible with E10 but recommend using a fuel treatment and stabiliser that will help keep your engine in top condition. Your  dealer will be able to source this for you and will be able to advise on how to use it when fuelling your machine.


Some Countax machines built in the early 2000s used Honda engines. Although compatible with E10, Honda do not recommend its use. Instead, they suggest using ‘Super Unleaded’ petrol which is currently remaining at E5.

We've put together a list of 'best practices' you should observe when using E10 petrol in your machine, please click here to read the article.