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E10 Fuel up-date for our customers

From September 1st (2021), all normal unleaded 95 Octane fuel will be made up of a mix of 90% regular petrol with the other 10% being Ethanol. This is called E10 fuel. Previously the mix was 95% Petrol/ 5% Ethanol (E5 fuel).


Ethanol is a plant-based alcohol and the reason for the change is to reduce overall carbon emissions. The disadvantage of the fuel is that the composition is slightly more volatile and can also degrade certain rubbers, plastics and even cause corrosion of some metal components when left standing for a period of time.


In modern cars and engines this new fuel will perform exactly as the previous E5 mix with no changes necessary, but with older cars and cars on which we have carried out engine conversions, the position is not so clear.


Our 2.3 GDiT (Ford EcoBoost) engine and our modernised fuel injected 4.8 litre Rover V8 both use components which are compatible with E10 fuel, but for engines which have retained older parts, and for carburettor engines, use of E10 should be considered with great care.

The main area of potential concern is all the various rubber hoses used in the fuel system. For many years we have bought hoses which are sold to us as being ethanol compatible, but unfortunately we have sometimes found this to be unreliable. We have not knowingly used incompatible material, but if a supplier has let us down, we only find out that there is a problem some time later when material starts to deteriorate. If you are planning to use 95 Octane E10 fuel now please regularly inspect any rubber hoses which contain or carry fuel around the area of the tank and up to the engine. The hoses might become soft or shown signs of surface cracking.



The modern plastic fuel tanks are compatible with ethanol, but be careful if using a metal tank, as corrosion can be caused by the Ethanol fuel.


If your engine has carburettors, there are plastic, rubber, and metal components which might be damaged by E10 fuel. The floats or needle valves in the float chambers might then fail leading to fuel flooding the carburettor.


If in doubt the safest solution is to use E5 fuel which is still available as the 97 or 98 octane ‘Super Unleaded’ fuel. If there has been no trouble with the car up to now, it should continue to be fine with Super Unleaded (check that it is E5 fuel).


With any car, if it is to be left unused for a period, we would recommend making the last fill-up before storage using Super Unleaded E5 fuel. When E10 fuel is stored for a long time the damage it can do gets worse. Where a car is being used everyday the fuel is being used up and changed regularly, and the problems are less severe.


If you are travelling and can’t find a petrol station selling E5 fuel, it will be perfectly safe to use E10 temporarily, but we would recommend topping up with E5 fuel as soon as possible.


For more information, the FBHVC published this helpful page : https://www.fbhvc.co.uk/fuels#Introduction%20of%20E10


If you have any concerns at all regarding an existing JE conversion, please contact the Engineering team here at JE and we will be happy to help.