E10 petrol: What is it and can my car run on it?

E10 petrol: What is it and can my car run on it?

First things first, don’t panic!

While some fuel stations have offered it since mid-August, E10 fuel has officially become the new standard grade at forecourts across the country with effect from today, replacing the previous E5 Standard grade.

But, what exactly IS E10 fuel and what do we need to know?

What is E10 petrol?

E10 is a biofuel made up of 90% regular unleaded and 10% ethanol – hence the E10 name.

The former E5 Standard unleaded fuel contained up to 5% ethanol and could be used in any petrol-engined car without problems or the need for modification. However, with E10, things aren’t quite so simple, which is why its introduction to the UK compared to other European countries, has taken some time.

Just how ‘green’ is ‘greener’?

It is estimated that the greener fuel could reduce CO2 emissions by 750,000 tonnes per year, the equivalent of taking up to 350,000 cars off the road.

What is ethanol?

Ethanol is an alcohol-based fuel produced from the fermentation of a range of plants, including sugar cane and grains, along with their by-products.

Unlike regular unleaded petrol, ethanol fuel is said to be partially atmospherically carbon-neutral. This is because as the plants that will become biofuel grow, they reportedly absorb more carbon dioxide than what will be released into the air during fuel production and combustion.

This partially offsets the greenhouse gas emissions produced by its production and use, but by just how much is still an active topic of debate.

Can all cars use E10?

No. Due to (perhaps, a convenient) miscommunication, the authorities have failed to mention that there are around 600,000 vehicles currently on our roads whose engines are not compatible with the fuel. You can see if your car is compatible with the new fuel by visiting the official E10 online checker.

Vehicles manufactured from 2019 onwards usually have an E5 and E10 label close to their fuel filler caps, showing which fuels they can accept. However, drivers of cars registered before 2002 have been advised not to use E10 in their vehicles, because problems have been reported. As of 2011, all new cars sold in the UK must be E10 compatible.

Drivers are advised to contact car manufacturers with any questions surrounding their specific vehicle. For example, Vauxhall says “E10 fuel can be used in all petrol-engine Vauxhall vehicles except models with the 2.2-litre direct-injection petrol engine (code Z22YH) used in Vectra, Signum and Zafira.”

Any other negatives with E10 fuel?

Sure…in colder weather, the higher ethanol content in petrol can make it harder to turn over an engine from cold. In addition, ethanol’s higher volatility can contribute to vapour lock (petrol becoming gaseous) when operating temperatures are higher, causing stalling.

Plus…ethanol’s high solvency can cause problems with many seal and gasket materials that are used in fuel systems, as well as with fibreglass resins. Besides a risk of fuel leaks, rubbers and resins can get partially dissolved, producing deposits that could foul carburettor jets.

Plus…ethanol can become acidic and cause corrosion of aluminium, zinc and galvanised materials, as well as brass, copper and steels coated in lead or tin.

My bad…I’ve put E10 in my older car. What now?

Don’t panic! If you accidentally put E10 fuel in an incompatible car it will still run. But seals, plastics and metals may be damaged over longer periods as a result of bioethanol's corrosive properties.

There have been reports that E10 is a less stable fuel and that this can make it more difficult to start a vehicle that has not been driven for an extended period.

The consequence of putting E10 fuel in an incompatible vehicle depends on the vehicle/engine variant and how much fuel has been put in. E10 fuel may cause some pre-detonation (‘pinking’), and perhaps a little rough running and poor cold starting, but it shouldn't be a disaster for the driver.

Unlike the fuel-tank draining consequences of a petrol-diesel misfuel, simply top up with the correct fuel suitable for the vehicle as soon as possible (ideally, when around two-thirds of the tank remains). All should be fine, but don’t make a habit of it.

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By Wayne Gorrett

Wayne has been covering developments in the UK's automotive sector for over 10 years, providing news, reviews, first-drive impressions and opinion pieces for a number of print and web outlets in the UK and South Africa. A former marketing director, Wayne is based in a rural village near Winchester, Hampshire. You can follow him on Twitter: @WaynesWorldAuto Facebook: WaynesWorldAuto Instagram: WaynesWorldAuto