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Everything you need to know about using E10 fuel with your classic car

by Nik Berg
17 June 2020 5 min read
Everything you need to know about using E10 fuel with your classic car
Photo: The Toms

It sounds like an additive found in food but from September E10 fuel will be causing headaches for hundreds of thousands of classic car owners. Rather than being a colouring agent or preservative, E10 is the new grade of unleaded petrol that the British Government will introduce this autumn. And it is potentially damaging to modern classics, classic cars and motorbikes alike.

Experts warn that the introduction of E10 is the most significant threat to old cars since the switch from leaded to unleaded fuel. Four-star fuel was banned in Britain from 2000, on environmental grounds. It’s for similar concerns over air pollution and CO2 emissions that E10 will be dispensed by the nation’s petrol pumps.

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However, the RAC has warned owners of cars built before 2002 that they should steer clear of the new petrol. It estimates that at least 600,000 vehicle owners will be affected. For those drivers, it is likely to mean increased fuel bills, costly vehicle maintenance or, for those that fail to take action, damage to cherished cars.

So what is E10 fuel, why is it being introduced and how can the classic car community prepare for the new fuel coming to our forecourts? Hagerty investigates.

What is E10?

Petrol in the UK already contains up to five percent bio-ethanol. You may have noticed as much; the labelling on unleaded pumps changed to E5 in 2019. But from September E10 will become the new standard with up to ten per cent bio-ethanol in the blend. Produced from crops such as sugar beet bi-ethanol isn’t a fossil fuel and is renewable.

Why is it being introduced?

It’s all about emissions. The Government has targeted 2050 as the year that Britain will reduce its greenhouse gas emissions to a net zero. But the journey starts now and by introducing E10 fuel they say that CO2 emissions could be reduced by 750,000 tonnes per year. That’s the equivalent of taking 350,000 cars off the road.

What’s the problem for classic cars?

Although many cars run on E5 without significant problems, doubling the amount of ethanol in the fuel can cause a variety of issues in olders cars. Ethanol is hygroscopic, which means that it absorbs water from the atmosphere. And that water, in turn, finds its way into your car. It can lead to condensation in fuel tanks, fuel lines and carburettors and cause corrosion in brass, copper, lead, tin and zinc components.

As ethanol is also a solvent it can eat through rubber, plastic and fibreglass, so hoses and seals are likely to perish more quickly because of the higher concentration of ethanol in E10. In Department for Transport tests, problems identified included degradation to fuel hoses and seals, blocked fuel filters, damaged fuel pumps, corroded carbs, blocked injectors and corrosion in fuel tanks. Rubber is particularly affected. The Federation of British Historic Vehicle Clubs (FBHVC) has a list of ethanol-friendly materials that can be used as replacements. [See end of story].

Finally, ethanol isn’t as energy dense as petrol, which means that the fuel-air mix could be leaner and, ironically, fuel consumption could actually be slightly higher than using E5 or ‘pure’ petrol.

How many cars are affected?

Although new cars sold in the UK since 2011 have had to be E10 compatible, the Society of Motor Manufacturers and Traders has estimated almost 8 per cent of petrol-engined vehicles here are not compatible with E10.

The RAC suggests that up to 600,000 cars on the road aren’t compatible with the new fuel. And it’s not just historic vehicles that are affected. Anyone owning a car made before 2002 is advised not to use E10 – and it can even affect cars made up until 2011. That’s a good number of so-called modern classic cars, in addition to classic models.

Why is the UK introducing E10 later than other European nations?

Phil Monger, Technical Director of the Petrol Retailers Association says the number of cars affected is fewer than in other countries: “Lots of European countries have already introduced E10. We’ve been working with government for the last couple of years and when we started this, we had rather more non-compliant vehicles, so we felt that we needed to introduce it at a later stage.”

Monger stresses that change won’t be made overnight and believes that many owners of old cars may have already made modifications since the introduction of E5 fuel. “Vehicles that are very old will have materials that will not be compatible with E5 either. E10 will only hasten the day when it causes you some difficulty with those materials.”

Is E10 a ‘greener’ fuel?

When E10 was introduced to petrol stations across Germany, in 2011, it faced a backlash from local green groups such as Greenpeace and the Nature and Biodiversity Conservation Union. The conversion of land to farms to supply bioethanol has linked to the destruction of forests and wetlands. At the same time, tests have shown that the fuel economy of vehicles using E10 is inferior to E5, raising questions over real-world CO2 savings.

What are petrol stations doing to warn drivers?

Everything you need to know about using E10 fuel with your classic car_Hagerty

The Petrol Retailers Association says that there will be an advertising campaign six months before the launch of E10 to advise drivers of the difference between the fuels. They will also introduce a website where you can check if a car is compatible, while on the forecourts fuel pumps will be labelled with a warning.

Needless to say, the introduction of such a website can’t come soon enough, and accurate, reliable information will be key to helping vehicle owners take appropriate action.

What is the alternative to using E10 fuel?

The good news is that super unleaded is set to remain at the E5 standard for five more years after the introduction of E10, according to the PRA. And most E5 currently only actually contains 2-3 per cent ethanol anyway.

The bad news is that it costs more – typically 15 pence per litre. So each time you fill up it could cost you an extra £6-10.

What can I do to protect my classic car?

Guy Lachlan, MD of Classic Oils, says classic car owners could face costly preventative maintenance. “You’ve either got to use fuel with no ethanol or change the materials that don’t like it,” warns Lachlan.

“If you are in any doubt about your rubber fuel lines, change them. Get rid of your fibreglass petrol tank and install an aluminium one. The other thing ethanol really doesn’t like is solder. If you are running a soldered float in your carburettor still then think about carrying a spare – they’re generally quite easy to change.”

Experts have also warned that even modern classics with turbocharged engines could be impacted by the switch.

Will E10 cause problems for cars in storage?

When it comes to storing your car, if it is older than 1996 and doesn’t have a catalytic converter, you can use a lead replacement additive such as Castrol’s Classic Valvemaster, which can help prevent corrosion as it also contains an ethanol stabiliser. It’s endorsed by the Federation of British Historic Vehicle Clubs.

For modern classics there are catalyst-friendly additives available such as Millers Ethanol Protection Additive or Lucas Oil Ethanol Fuel Conditioner, but your best advice is to check with the vehicle manufacturer or an owners club.

The other option, says Lachlan, is to make sure that you don’t give the ethanol a chance to absorb water from the air by filling the tank fully, sealing it, or conversely, fully draining it before storage. (Hagerty has more tips for prolonged storage of classic cars, here.)

What if I fill up with E10 by mistake?

The RAC advises that, unlike putting diesel into a petrol car (or vice versa) you shouldn’t need to drain the tank. It could cause pinking and make it harder to start from cold, but one fill-up shouldn’t cause lasting damage. Just try to top up with E5 as soon you can – ideally when you’ve used at least a third of the tank – and don’t leave the car in storage until you’ve done so.

Where can I find more information about E10 and classic cars?

There is a wealth of information on the website of the FBHVC, including detail of the materials that could be adversely affected by the ten per cent bioethanol mix, and approved after-treatments that can help guard against corrosion.

For younger vehicles, car manufacturers and their franchised dealers should be able to provide guidance. Alternatively, for older models, seek advice from a reputable local garage or your chosen specialist for your classic or modern classic car

Will synthetic fuels ride to the rescue of classic cars?

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  • John Mullen says:

    I believe ethanol up to 15% was in fuels like Cleveland Discol up to the 60s. Their ads. said ” Its the alcohol that gives more power” and such like. So cars of that era have lived with it before, I do remember that petrol pump diaphragms used to fail more often then.

  • Malcolm Dodd says:

    First reaction to the ethanol story is why not mix E10 with super unleaded at 50/50 or maybe 40/60 to achieve present E5 levels?

  • Mike Appleyard says:

    having flown model aircraft for many years using 80% Methanol I wonder if the ‘problem’ is being over stated. Methyl and Ethyl are very closely chemical related and I can say that problems are basically non existent. also the much lauded aluminium corrosion does not occur in our 90% alloy engines and peripherals so maybe time for some proper testing, not just listening to perceived wisdom – remember the millennium bug?!!

  • Cliff Doe says:

    I inadvertently filled the tank of my 1972 Porsche 911 with E10 fuel in Denmark on a return journey to the UK. It made for a very uncomfortable journey particularly in low speed areas. When back in the UK the cure was to fill with Super Unleaded ASAP, a fuel that I continue to use. Future continental fill ups will have Millers VSPe Power Plus additive at 50ml to 50L petrol to prevent ethanol corrosion

  • Cliff Doe says:

    I inadvertently filled the tank of my 1972 Porsche 911 with E10 fuel in Denmark on a return journey to the UK. It made for a very uncomfortable journey particularly in low speed areas. When back in the UK the cure was to fill with Super Unleaded ASAP, a fuel that I continue to use. Future continental fill ups will have Millers VSPe Power Plus additive at 50ml to 50L petrol to prevent ethanol corrosion and boost the octane rating.

  • James Mills says:

    Cliff, really interesting to hear of your first-hand experience of this issue. How was the 911’s engine after you’d run the fresh tank of Shell V-Power through it? Is everything okay now? And would you consider speaking with me about this, please, via

  • richard howard says:

    Well we have super unleaded til 2025 so plenty of time to just have to use additives.

  • PdK says:

    As I work in the sugar industry, my comments might not be a little hard-to-swallow. 1 Ethanol is hygroscopic, which means any groundwater-leaching in underground petrol storage tanks at filling stations is better dealt with when ethanol is included. 2 Perished rubbers should be replaced by owners, no ifs no buts. 3 Ethanol is 30% less dense than petrol, therefore lower MPG – obviously. But at E10, there should be no difference because…. 4 any blend below 20% is simply an oxygenate replacement (instead of nasties like Toluene) and improves combustion as a result. 5 E5 will still be available for the next 5 years, so this is really about the minority holding up progress. 6 Food vs Fuel is no longer relevant today, the main global issue today is food access (and the fact that some in the world are going hungry while others are dying from excess). 7 Cold starting is not an issue until you get to above E85 (the balance 15% petrol prevents this issue). 8 The 10p additional cost is partly because ethanol is cheaper than petrol, it is also less-taxed. If you want cheap fuel, you should consider E85 like they have in France. 9 Any car owner who still things petrol is a single product is wrong, it is a blend of many chemicals in order to comply with environmental regulations. Changing one chemical for another is a continuous process, the only difference is that this one is not produced by oil majors.

  • Stuart says:

    can I use this new fuel in my lawnmower?

    • James Mills says:

      That’s a good question, Stuart, and will depend on the year of manufacture. The best advice would be to check with the manufacturer. Let us know what they say.

  • Robert dwen says:

    They want us to use electric motor is not petrol

  • Gary Purser says:

    I only own classic cars.. I know my mpi mini is OK.. As its fuel injection not carbs.. But i cannot find my MGF vvc in any list of compatible cars…

  • B .figes says:

    It is possible to remove most of the ethanol from the fuel . I’ve been doing it for sometime.I also use additives

  • Sanjay Shabi says:

    To add further balance. This does not mean E5’s future is finite. Available via Google for all to digest, the Federation of British Historic Vehicle Clubs’ press release dated 6th March 2020 reveals just prior, the Government published a consultation on proposals to introduce E10 petrol as the standard for fuel across the UK. Within it, the lead proposal would introduce a minimum ethanol content of 5.5% for standard ‘premium’ fuels in 2021, whilst – and this is important for historic vehicles – maintaining the current E5 blend in the ‘protection’ grade.

    The same day as the consultation was announced, FBHVC Chairman David Whale attended a meeting at the House of Commons with the All Party Parliamentary Historic Vehicles Group, chaired by Sir Greg Knight, to reinforce the concerns of the Federation’s members directly with MPs. Rachel Maclean, Parliamentary Under-Secretary (Department for Transport) abridged response acknowledged E10 threat to older engines. “For those vehicles, the Department remains committed to ensuring that E5 is retained as a protection grade, if E10 is introduced.” Possible storm in a fuel tank?!

  • Alastair Queen says:

    The above link is to the result published following tests conducted at Manchester University, using an old technology engine, and various fuels easily available.
    If ethanol is going to be a worry to old vehicle owners, then buy the book, and give it a thorough read, several times, to understand how today’s petrol affects old technology motors.
    The tests showed that, effects on old or marginally maintained fuel systems aside, old technology engines will likely run better on E10, than they did on current, or part fuels.
    Its largely down to the ethanol offsetting the effects of a phenomenon known as cyclic variability.
    The book is certainly worth a read. The results may also debunk much of the urban myth currently doing the rounds regarding ethanol in petrol?
    Perhaps even the RAC, and the authors of this article should also take a look?

  • James Cogan says:

    E10 is suited for use in all petrol engines no matter the age, make or model.

    The RAC adopted the extremely conservative and mistaken assumption that “Where no information was available it was assumed they were incompatible” when reading EU manufacturers’ decade-old legal positions on E10. But there was information available, and lots of it, which the RAC should have considered before publishing such important and misleading guidance. E10 has been the standard in the USA for decades and is used in all makes and models of cars including vintage cars, and not a single incident of E10 incompatibility has been reported. There are no differences in materials or engine technologies between the USA and the UK. The notion that E10 might not be suited to some vehicles has been redundant for decades in the USA. There are numerous reports and studies to this effect. A dozen EU countries use E10 and while most of them also offer E5 there have been no incidents of people inadvertently filling up with E10 and experiencing adverse consequences. All told, E10 is the standard fuel in regions with fleets totalling half a billion petrol vehicles and there simply aren’t any issues.

    The hypothetical “issues” that supposedly arise from ethanol being hygroscopic or corrosive remain just that: hypothetical. Real world empirical evidence on a massive scale conclusively demonstrates the owners of vintage cars may use E10 with full peace of mind. None of the negative theories stand up to scrutiny.

    In a few years from now UK drivers will have forgotten the matter. In the meantime journalists will be tempted to uncritically copy and paste the RAC’s misleading guidance, propagating it further. There will be much unnecessary anxiety and cost arsing from it (maintaining E5 in parallel with E10, etc).

    For more on this: and

    Note: Hagerty Insurance in the USA has been involved in dedicated research for car collectors to investigate the possibility of long-term effects on vintage vehicles of ethanol blended petrol. From 2006-8, Hagerty, together with the Kettering University Advanced Engine Research Laboratory conducted a comprehensive study to address that concern. The research determined that there was no difference in performance between carburetor engines running E10 and those with more modern direct injection systems.

    I hope this is helpful.

    Best regards,
    James Cogan, 14 October 2020

  • Peter Malin says:

    I believe the greatest concern must be for owners of early fuel injected vehicles. If fuel line degradation is an issue it’s less of a problem for a carburettor engine, fuel is essentially sent from fuel tank to engine via a pump and the carb. and a straight forward fuel line. Fuel injection engines however, generally have vehicle specific pipes with banjo fittings to connect them. The cost of replacing these, often difficult to find pipes, could be considerable….imagine something such a Jaguar V12 , the cost of replacing all the fuel lines in one could well ruin you!

  • Dr Paul Ireland says:

    Research performed at Manchester Universality looked at the problems of running classic cars on modern fuel. The tests included E10. This research has been published in a popular book Classic Engines, Modern Fuel. It may come as a surprise to the author of this article that classic engines run better when using E10.
    Like many other on E10, this report is little more than scaremongering. Yes the issues it raises do cause some problems but they really are not as bad as they are portrayed. What is worse it does not report on the most serious problem with any ethanol blended fuel. One that can be easily avoided if you know about it.
    I suggest readers look at a definitive report that is based on real research that puts the problems caused by ethanol blended fuel into perspective.

  • Ash says:

    Hi there..ok so on the subject of using additives..anyone use Tetraboost? The only ‘real’ lead fuel additive??
    I own a couple of pre 1972 classics aswell as a 1949 cadillac..would this the better option to use? Any advice would be grateful..thanking you

  • Henri De Vrin says:

    Working as a trader of used trucks & buses, I advise to be careful when leaving a fuel tank, filled with ethanol (I had some city buses running on ethanol) After a while (more than 1 month) I had problems with algae formation, which blocked fuel line as a result.
    Also, think about your motorbike, where fuel tank is higher than fuel pump or fuel regulator valve!

  • Mr B.B. Payne says:

    I have a 1964 Singer “Vogue” 1600 cc, c/i ohv ( unleaded converted) and 2 yrs ago I filled a jar with E5 petrol and put a sample of parts ,ie, brass, alloy, steel, rubber, AC pump diaphram, etc and as now Feb 2001 I have not noted any serious problem when i examine them, As someone pointed out, Ethanol was advertised as an upgrade fuel for years ie, “DISCOL” etc so why all the panic?

  • Edward motocyclism says:

    Edward motocyclis

  • Edward motocyclism says:

    My main concern is the effect on rubber in the fuel system, I have already had to replace the fuel taps on my Triumph Bonnville because the swelling of the rubber made turning on and off of the petrol taps very very tight(snapping off lever tight). The corroding of carburettor alloys is a worry as I also have two Japanese bikes and then the elephant 🐘 in the room, my beloved mk 2 golf GTi, there are rubber parts and o rings in every part of the fuel system, will I be able to get an ethanol o ring kit for the metering head, fuel pump and accumulator, notwithstanding the injector lines and o rings.

  • BENNY says:

    Ethanol fuel used on carburettor motorbikes in freezing winter conditions result in carb icing -low power and stalling.additives needed to resolve the issue.
    Frequent blockages to two stroke carb jets.unable to start.
    Fuel degrades quickly.
    Causes many additional maintenance problems.

  • Bill Fletcher says:

    Already affected by E5, destroyed the fuel pipe on one lawnmower and rotted the float needle tip on another. I also fly a microlight that has fibreglass/ carbon fibre fuel tanks bonded into the structure presently I drain the tanks after every flight but I can’t remove fuel from the carburettor and there will be some residue in the tanks, do I just accept it rots as I fly?

  • Colin King says:

    I run a 1964 MGB. It has the standard leaded head and I use an lead replacement supplement in ordinary E5 petrol. I am now confused after reading all of these posts. Do I keep running as I am or can I use the E10 or super unleaded?

  • Richard Smith says:

    When I first started driving, about 1967, it was common to give a squirt of redex into the tank for every gallon of petrol. I believe this will become the norm again with the required additive for older cars.

  • Richard Janssis says:

    I am totally confused over the whole issue of E10. I have owned my Morgan plus 8 for 35 years and don’t plan on getting rid of it any time soon. I would ask those in the know to give the matter some objective analysis and then publish a definitive response to the problem. If E10 genuinely poses a problem, then someone please come up with a solution. With so many car enthusiasts, engineers and motoring organisations, when will we be given clear guidance on this issue?
    Thank you in anticipation of some useful information coming soon.

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