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02 Aug 2023

Photos by Jayson Fong

How do changes in fuel blend affect you?

Club partners WEX break it down so your engine doesn’t have to

In September 2021, the British government introduced E10 fuel (fuel containing 10% ethanol) as standard across the country as a method of combatting the climate crisis.
E10 fuel is typically not compatible with some classic cars so, in order to keep classic wheels turning, Esso Synergy Supreme+ 99 was left at only 5% ethanol and some parts of the country, such as Devon, Cornwall, Teesside and Scotland, continued to sell fuel that was completely ethanol-free. However, as of 1 September 2023, this will no longer be the case and Esso Synergy Supreme+ 99 will contain up to 5% ethanol at all Esso pumps, irrespective of which part of the country they are located.
While the ethanol content of the fuel will be changing, there will be no change to the minimum research octane number (RON) of 99.0, which mirrors the UK’s highest octane premium fuel. The RON quantifies the combustibility of fuel at both low temperatures and speeds. The higher the RON rating, the better because this indicates a higher quality, more efficient fuel. Using a higher-octane fuel results in an improved fuel economy, power and acceleration. Higher octane fuels can also help reduce ‘knock’, which occurs when air and fuel ignite in the engine without a spark.
In older and classic cars, ethanol could potentially have some negative effects such as corrosion in fuel tanks and loosening debris within your engine. However, a Super-Unleaded petrol with up to 5% ethanol is classed as a ‘protection grade’ for cars which are not able to run on E10. Additionally, there is no need to flush your tank, so Esso Synergy Supreme+ 99 is perfect for those who want to fill up and hit the road. 
Wait, there’s more
Esso Synergy Supreme+ 99 offers two detergents, a corrosion inhibitor and a friction modifier to help protect your engine and improve its’ overall health.
Thanks to this and other preparations, the introduction of E5 in Esso Synergy Supreme+ 99 across the country will have next to no effect on your Porsche as Esso continues to help protect our planet.
Do you want to learn more about Esso Synergy Supreme+ 99 and how it can help your Porsche? Check out for more information.
Claim your free Esso Card™
The exclusive PCGB-branded Esso Card™ is available now and allows Club members to save 6p per litre on Esso’s Synergy Supreme+ Unleaded (SU99) fuel. Apply online at
Your membership number, which is required for the application is available here.  

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