Author: Craig Cheetham
Photography: Craig Cheetham
Modern fuels and old fuel lines aren’t the perfect mix. But how do you make sure your car is safe with today’s petrol…
It’s now over three years since E10 fuel – which has a 10 per cent ethanol blend – was standardised across the UK’s petrol pumps, yet despite initial concerns, most of our classics are still going strong. But is that down to careful maintenance, or more because the cars we’re using aren’t as badly affected by sustainable fuels as we first thought?
The answer is, of course, not straightforward, with two main concerns around the use of E10 fuel that need addressing – one relating to safety and the other relating to longevity.
The main safety concern for classic cars running on modern fuel is that the higher ethanol content of E10 petrol can degrade older components, attract moisture, and affect rubber components such as old fuel lines.
Older fuel systems were not designed for ethanol-blended fuel and with ethanol being essentially a solvent, it can slowly dissolve or degrade incompatible materials like certain rubbers and plastics. This could lead to leaky hoses and perished seals.
Reliability concerns are also centred around its solvent content – ethanol is hygroscopic, which means it absorbs water from the atmosphere. Put simply, if a car isn’t used frequently enough to regularly have its fuel supply replenished, water can accumulate in the fuel tank, fuel lines, and carburettor or injection system. As well as internal corrosion, this weaker fuel mixture simply isn’t as stable and won’t burn as well.
Ethanol can also dislodge old deposits from the fuel tank and lines, blocking filters, jets, injectors and carburettors. So why haven’t all our cars conked out?
Keep it moving
By far the most effective (and most enjoyable) way of avoiding ethanol-mix fuel problems is to keep using your classic as much as you can, so that the fuel doesn’t have time to ‘go off’, or to sit in your tank and fuel lines.
Even if your classic is stored off the road for winter, taking time to start the engine and run it up once every couple of weeks will keep the fuel system flowing and eradicate any moisture.
Cars have always liked being used – it’s what they’re designed for, after all – and it’s the best way of keeping your fuel system in good health.
Should I use E5 instead – and are there any other alternatives?
Certainly for older classics, which were designed to run on higher octane fuel in the first place, E5 makes sense – it varies between 97 and 95 Octane and will help prevent pinking on older engines, plus will make them run more efficiently.
If you only use your classic occasionally, then some places do still sell ethanol-free fuel. You can order it from Anglo-American Fuels, Classic Fuel Solutions, and MotorSpirit, for example, but it isn’t cheap and needs to be stored securely.
Other options are to add fuel stabilisers such as Merlin Motorsports Ethanol Protection, which reduce the hygroscopic effect of pump fuels.
It’s also worth looking at SUSTAIN, from Coryton Fuels, which is a sustainable fuel with less than one per cent ethanol content, but its availability is limited.
For most users, E5 (or Super Unleaded) is a viable and widely available option that will be more stable over time than E10.
How is it best to store my car?
If you’re laying your car up for a very long time, then the best advice is to drain the tank, or leave it with a minimal amount of fuel in it – fresh fuel should be sufficient to cause no major issues when you’re putting it back on the road.
If you’re putting it away for the winter, though, then the opposite is arguably better – fill the tank completely with fresh E5 and a stabiliser to help prevent condensation, so that water doesn’t get into the fuel system.
How can I futureproof my classic against prolonged E10 usage?
Yes, you can – and this is the best long-term solution. The key is to replace parts that aren’t perfectly compatible with ethanol-based fuels.
This should include replacing old rubber hoses, seals, gaskets, and fibreglass tanks with compatible materials such as silicon, polyethylene, braided or stainless steel – a worthwhile winter project if you’re putting your car in the garage for a few months.
Is E10 really a bad thing for classics?
Well, here’s the rub. It all depends on your car. Most ‘modern classics’ will continue unabashed, with no real issues. This is largely due to ECU-controlled fuelling systems, which since the mid-1990s have been harmonised to adjust how the engine operates based on different fuel grades across the world, so unless you have a particularly sensitive high-performance car, then providing you follow our advice around storage, its use is unlikely to cause major issues.
On older models, though, the risks are greater and we’d very much recommend the use of E5 fuel in addition to a fuel stabiliser, and to check your fuel system components as often as you check your oil and coolant – it’s cheaper, safer and less heartbreaking than losing your classic in an inferno, after all…
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