What do the numbers on the pump mean? (E5, E10, B7)
Published - 4 min read
A plain-English guide to UK fuel pump labels - E5, E10, B7, XTL and LPG - plus octane ratings, AdBlue, and what to do if you use the wrong fuel.
Why the labels exist
Fuel pumps and nozzles in the UK carry standard labels that describe the fuel inside, so you can match it to your vehicle. Since late 2018, new cars have carried matching labels, usually near the fuel filler cap or in the handbook. The shape tells you the type of fuel:
- Circle - petrol
- Square - diesel
- Diamond - gaseous fuels
Petrol: E5 and E10
- E10 - petrol with up to 10% ethanol. This is standard unleaded in the UK.
- E5 - petrol with up to 5% ethanol. Usually sold as super or premium unleaded.
Not sure which your car can use? See E10 vs E5: which petrol should you buy?
Diesel: B7 and others
- B7 - diesel with up to 7% biodiesel. This is standard diesel at UK forecourts.
- XTL - synthetic (paraffinic) diesel, such as HVO made from renewable oils. Some stations sell it; only use it if your vehicle's manufacturer approves it.
- B10 and other B numbers indicate higher biodiesel blends. Check your handbook before using anything other than B7.
Gases: LPG and others
Diamond labels include LPG (liquefied petroleum gas, sold at some forecourts for converted and dual-fuel cars), CNG and LNG (compressed and liquefied natural gas) and H2 (hydrogen).
Octane numbers (RON)
Petrol is also sold by its octane rating, shown as RON (research octane number). Standard unleaded in the UK is at least 95 RON; super unleaded is typically rated between 97 and 99 RON. A higher number means the fuel is more resistant to "knocking" (uncontrolled ignition), which matters for some high-performance engines. It doesn't mean the fuel contains more energy. Use what your handbook recommends.
The price display
UK pump prices are shown in pence per litre, to a tenth of a penny - which is why so many prices end in .9. As you fill, the pump shows the litres dispensed and the running cost. You can compare prices at nearby stations on the live map.
Nozzle colours aren't a guarantee
At many UK forecourts petrol nozzles are green and diesel nozzles are black, but this isn't universal, so always read the label. Diesel nozzles for cars are often wider than a petrol car's filler neck, but a petrol nozzle usually fits a diesel car - which is why putting petrol in a diesel car is the more common mistake.
AdBlue is not fuel
AdBlue is a fluid used by many modern diesel vehicles to reduce exhaust emissions. It goes in its own separate tank, usually with a blue cap - never in the fuel tank.
Put the wrong fuel in?
- Don't start the engine - or if you've realised while driving, pull over safely and switch off.
- Tell the forecourt staff and call your breakdown provider or a fuel-drain service.
- The fuel will usually need to be drained from the tank before you drive on.