Petrol E10 is here: what do you need to know?

Petrol E10 is here: what do you need to know?

It’s been a long time coming and there’s been much discussion within the classic car world about it, but E10 fuel is now in the forecourt pumps and the government advertisements have started appearing on billboards.

As its name suggests, E10 petrol contains up to 10 per cent ethanol, twice the proportion of the E5 grade which has been the standard for the last decade. The issue of ethanol in fuel has long been a hot potato in the classic car world but at the lower concentration of the E5 fuel has proved not to be a problem in practice. However, the E10 grade has people worried about its effects on older cars.

There are two big issues with ethanol fuels and older cars. The first is that ethanol can have a corrosive effect on metal, plastic and rubber parts in the fuel system. The results of this can range from the inconvenient, like sticking carburettor floats, to the dangerous when fuel lines perish.

Crucially though, not all vehicles will have problems and rather like the introduction of unleaded fuel back in the ’80s, some will be perfectly happy on the new fuel and some will need modification.

The second issue with the E10 fuel and something which is more of a problem for classic cars than everyday modern vehicles is that the ethanol is hygroscopic, meaning it tends to absorb water. Clearly the longer a car is left standing idle, the bigger an issue this will be, with any moisture in the fuel only adding to potential issues.

So what can classic owners do about it? Owners of modern classics can use the government’s online checker tool at www. which uses information supplied by car makers as to the suitability of the fuel system. Information is patchy but has improved since the online check was first offered and for many brands the system will go as far back as the early ’90s. Some marques, especially the German brands, go back even further: Volkswagen for example simply states that all its engines can run on E10 fuel except for a few FSI units from the early 2000s, while BMW flatly states that all its cars can use E10.

More modern future classics also escape the issue, since all new cars have been capable of using E10 fuels since 2011.

Clearly though, this doesn’t help owners of older cars, so what options do owners of traditional classics have? Well the good news is that the technology exists to upgrade the fuel systems to cope with the new fuel. In truth, it’s good practice to renew ancient fuel lines as a precaution in any case and modern fuel hose sold by a reputable supplier is rated for use with E10. The commonly used SAE standard follows the J30/Rx rating, with the current J30/R9 being the accepted choice for modern fuels and rated at 100psi. The higher ‘R’ rating doesn‘t necessarily mean the hose is any better for ethanol fuels, though: R10 for instance is for submerged hoses but doesn’t like underbonnet heat, and R14 is for lower pressure applications than R9. However, this may not in fact be necessary since the regulations require larger forecourts selling two grades of petrol to continue selling E5 fuel. This will be offered only in the more expensive Super Unleaded grade however, which brings its own problems: even the bigger petrol stations often only have a single Super Unleaded pump, and in rural areas it may be hard to find a retailer large enough to stock it. The Super Unleaded is also a more expensive fuel, with the price gap potentially set to widen further in time.

We’ll be keeping a close eye on further developments but in the meantime the options for drivers of older cars are clear: if your car isn’t covered by the DfT online checker or is deemed unsuitable for E10, then you can either use the more expensive Super Unleaded or can update the fuel system and use a fuel stabiliser additive when the car is left for long periods.

WHY E10?

In theory the use of E10 petrol is an environmental move, intended to reduce the fossil fuel component of vehicle fuels and therefore combat climate change. Rather than emissions or air quality, the goal is reduced CO2 emissions and it’s thought that by doubling the proportion of the renewable component in the fuel (the ethanol) a 750,000-tonne reduction in CO2 is achieved – the equivalent of taking 350,00 cars off the road.

It’s not all good though. The fuel is slightly less energy dense, meaning an economy reduction of up to 1%, but what’s not widely known is that since 2016 new cars have been certified for emissions and performance using E10 fuel.


Regular readers will be aware that a non-profit organisation was recently created to support the interests of the classic car industry in the UK, which is judged to be worth some £18.3bn to the economy. Separate from the FBHVC, the Historic & Classic Vehicles Alliance intends to ensure that the classic vehicle sector is properly represented at all levels and recognised as the sustainable industry it is.

Part of the HCVA’s aim is to ensure that when regulatory issues crop up which threaten the sector, dialogue with government beforehand can ensure that solutions are worked up before the problems arise. HCVA spokesperson Malcolm McKay commented: “our aim is to persuade government to keep all the options open on fuels for the historic and classic vehicle movement. As you know, they have already allowed the continued sale of E5 and that dispensation can be renewed — but the key factor will be demand, as if it is not used, retailers will not stock it and petrol companies will stop producing it. We need to encourage everyone to fill up with it if we want to keep it!” In the longer term, the HCVA hopes to encourage the development of synthetic ‘eFuel’ as a means of keeping combustion-engined classics on the road with a low or zero-carbon footprint – a decidedly more green option than scrapping them. More at

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