E10 Petrol - Advice for Classic Cars

Posted on 15 November 2021

E10 Fuel - Thornley Kelham’s advice for classic car owners. 

 November 15, 2021

The nationwide rollout of E10 fuel has created a problem for owners of pre – 2005 cars, including classic Porsches and all Lancia models. E10 contains between 6 and 10% bio ethanol, which will have a detrimental effect on these models and can be potentially dangerous. All standard unleaded petrol is now E10 grade. 

However, help is at hand for our cherished cars in the form of filling up with Super Unleaded fuel rather than regular 95 octane unleaded. For the time being, the UK Government has left the quantity of bio ethanol at 5% in most super unleaded, which is not enough to damage the cars or their fuel system components.  

Better still, one fuel company* produces a Super Unleaded petrol with zero bio ethanol content and that company is Esso. Thornley Kelham recommend filling your tank with Esso Synergy Supreme Plus (SU99) wherever possible. If this fuel is unavailable in your area, simply fill the tank with any other Super Unleaded petrol. 

*Currently unavailable in Devon, Cornwall, North Wales, Northern England and Scotland.      

For those who wish to be able to fill up occasionally with E10, Thornley Kelham stock an additive which prevents corrosion caused by the ethanol. One 500ml container treats up to 500 litres of petrol. This is a compromise solution only, so should be used when no Super Unleaded is available. Ask for EPS Multi Shot. 

If your car is going to be stored for any period of time and you have a mixture of 95 and 98 Ron petrol in the tank, Thornley Kelham recommend you add Tank Safe to the fuel tank. This product provides protection from the harmful and corrosive compounds found in E10 fuels. 

Owners who wish to make their cars suitable for use with E10 fuel permanently, will need some component changes to their vehicle. The following require upgrades: 

  • Fuel pumps 
  • Fuel lines and petrol pipes 
  • Carburettor floats 
  • Pump jet diaphragms 
  • Petrol tanks need internally coating if steel or aluminium 
  • Carburettor jets and needle settings 


We trust you will find this information helpful. Please do not hesitate to contact Thornley Kelham for more advice if required, or to book your car in for a service for the works described above.

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