Transition from E5 to E10 Petrol:

E10 petrol is being introduced into the UK from September 1st, 2021 and will become the standard 87 octane regular unleaded petrol.

E5 will still be available in the 95-octane super unleaded petrol.

What is E10

E10 petrol is made up of 90 percent petroleum-based petrol and 10 percent ethanol. Ethanol is an alcohol-based fuel produced from the fermentation of a range of plants, including sugarcane and grains, along with their by-products.

Unlike regular unleaded petrol, ethanol fuel is said to be partially atmospherically carbon neutral. This is because as the plants that will become biofuel grow, they reportedly absorb more carbon dioxide than will be released into the air during fuel production and combustion.

Petrol with up to 10% ethanol (E10) by volume is acceptable

Keep in mind that ethanol fuel blends will absorb water from the atmosphere and can cause corrosion of fuel system components. Since most carburetors and the petrol tanks are vented to the atmosphere in some manner there is nothing to prevent petrol from absorbing moisture over time.

Using fresh petrol (less than 30 days old) will help prevent water absorption from becoming a problem.

Temperature variance can cause condensation to collect inside your storage tank if it is not properly sealed. Store in dry areas, with low humidity. Ethanol will absorb any condensation that forms inside storage containers.

Do not use petrol with more than 10% ethanol by volume.

Engines produced to date for use in outdoor power equipment are not designed for petrol with more than 10% ethanol (such as E15 and E85); using higher ethanol fuel blends may lead to engine damage and/or performance issues.

How to minimise fuel system problems

Purchase only the amount of fuel that will be used within 30 days

Petrol deteriorates over time. Deterioration begins with the most volatile compounds evaporating. Once evaporation reaches a certain point it will be hard/impossible to start the machine. As more compounds evaporate, the petrol will form brown gummy deposits in the system. Given enough time the gummy deposits will become a hard varnish. Gummy deposits and varnish can plug passages in the carburetor preventing the engine from running or causing the engine to run poorly (e.g., surging, lack of power, stalls, etc.). Deposits can also cause the carburetor to leak fuel if they prevent the float needle from sealing properly.


In vented fuel tanks and fuel systems the rate of oxidation increases

Add fuel treatment / stabiliser.

A fuel treatment should be used to minimise the oxidation rate of the petrol and extend the storage life. Always add the fuel treatment to the container filled with new pump purchased fuel on the day you buy it, never into the fuel tank of your lawnmower.

There are two types of fuel treatment / stabilizer:

  1. Form a layer over the top of the petrol and greatly reduce the rate the fuel’s volatile compounds evaporate. They also prevent absorption by the fuel.
  2. Protects the petrol at the molecular level and does not just form a film on top of the fuel.

Fuel treatment works at the molecular level and has three key functions:

Fuel stabiliser – Protects the fuel by bonding with the petrol gas molecules at a chemical level which prevents the fuel from oxidizing.

Cleaner Additives – Cleaners in the additive neutralizes and decomposes carbon and gum deposits

Corrosion Inhibitors – Forms a barrier on metal parts of the fuel system against rust, oxidization and corrosion.


All current production machines using Hayter, Toro, Briggs and Stratton, Honda, Kohler or Kawasaki engines can safely use E10 fuel, but no higher.

For older machines we recommend that you refer to your Engine Operators Manual for guidance.

As a general guide Machines produced from the following dates are compatible for use of E10 fuel:

Year Engine Brand

2000 Hayter, Toro, Briggs and Stratton, Honda

2011 Kawasaki

2020 Kohler

Prior to these dates engines may not be compatible but clarification should always be made via the Engine Operators manual or engine manufacturer. Please click here for the fuel stabiliser.