Can I Use E10 Fuel In My MX5? - MX5 Parts Info
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Can I Use E10 Fuel In My MX5? - MX5 Parts Info

All About E10 Fuel and Your MX5

There are plenty of scare stories doing the rounds about the shift to E10 fuel and older cars – fear not, we’re here to help and cover all you need to know.

It’s not all doom & gloom

While you’re in safe hands here on MX5 Parts you shouldn’t believe everything you read about the widespread introduction of E10 fuel to British filling station forecourts, and the apparent fears it will wreck the fuel systems of older cars like many of the Mazda MX5s we all enjoy. Suffice to say, we have been doing our homework, talked to the people in the know and it’s not as scary as many doom-mongers are making out.

What is E10 fuel?

Let’s start with the basics, though. E10 fuel refers to a new ‘standard’ grade of petrol being introduced from the summer of 2021, replacing the traditional ‘95RON’ unleaded we’re all familiar with. In simple terms the name refers to the increased proportion of ethanol in the fuel, this now accounting for 10 per cent of every litre of unleaded you buy from a regular pump. The higher-octane fuel generally known as ‘super unleaded’ (or sold under branded names like Shell V-Power) will stay as it is, which is to stay at five per cent ethanol or E5.

Government attempts to reassure drivers it’s nothing to worry about have, to use an opportune turn of phrase, slightly poured fuel on the fire though, the assertion that “almost all (95%) petrol-powered vehicles on the road today can use E10 petrol and all cars built since 2011 are compatible” hardly encouraging for MX5 fans, on the basis many of the cars we drive seemingly fall outside of that. And when you enter ‘Mazda’ into the ‘Check your vehicle is compatible with E10 petrol’ tab it says “E10 petrol is cleared for use in all models with petrol engines introduced in and from the year 2002”, which sounds like bad news for owners of Mk1 and Mk2 MX5s in particular.

An engineers view

A quick chat with our friends at MX5 Restorer proves the realities of the situation are rather less dire than some are making out. Engineering graduate Ollie Carter from MX5 Restorer has even made a video explaining in some detail why don’t need to worry, which you can check out on the Lights Up Lights Down YouTube channel here. Click below to play…


Short version? Fears the supposedly ‘acidic’ ethanol will eat through your fuel lines and destroy the injectors on older MX5s are actually way off the mark, both in terms of the actual chemistry of the fuel and the fact the older parts in the fuel system are actually the same as the more recent (and officially compliant) ones. As Ollie points out, the age of Mk1 and Mk2 MX5s, and the fact all the components in the fuel system are service items that will need renewing at some point in the car’s life, mean you may well be replacing them anyway as part of your ongoing servicing. And if that’s the case you know who to call! (See our useful link section below to Fuel System parts for your MX5)

Is Ethanol bad for your car’s engine?

But what about increased wear to the engine internals? Again, a myth! As detailed in a video by Engineering Explained, E10 petrol was evaluated in detail against regular unleaded and methanol in various combinations in a study by the Society of Automotive Engineers (SAE) sponsored by the US Department of Energy and US Army as far back as 1981. In pretty much all the tests the E10 fuel inflicted no additional wear on engine components, and in some cases was actually better. And, as Ollie Carter points out, the increased ethanol content can actually help clean up engines, much as the additives in existing super unleaded do.

And, if you’re really worried, that E5 ‘super’ will remain on sale alongside E10. It will obviously be more expensive but, ultimately, your choice to use it is exactly that, not a necessity.

It’s true the chemical composition of E10 means it can absorb water through condensation if a car has been left standing for long periods, and that can have a corrosive effect on fuel tanks and lines and dry out seals and other rubber components. But the same is true of regular unleaded too.

The solution?

As it turns out it’s pretty simple. Stop worrying. And drive your MX5 more, on the basis cycling fresh fuel through the system is much better for it than leaving it standing. And that’s advice we can all live by!

Useful links

Special thanks

Thanks to Ollie at MX5 Restorer for his expertise and insight