E10 vs E5 Petrol: What's the Difference and Which Should You Use?

Summary

• E10 is Now Standard: Since September 2021, E10 petrol (10% ethanol) is the default at UK pumps.
• E5 is Still Available: Super Unleaded (97 octane) is still E5 with only 5% ethanol.
• Check Compatibility: Most cars made after 2011 can use E10. Older cars may need E5. Check our fuel guide for details.

You've probably noticed something different at the petrol pump. Where it used to just say "Unleaded," it now says "E10." And what happened to normal petrol?

Don't worry—it's simpler than it looks. Let's explain exactly what E10 and E5 mean, and which one your car needs.

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What Is E10 Petrol?

E10 is petrol that contains up to 10% bioethanol. The "E" stands for ethanol, and the "10" is the percentage.

What Is Bioethanol?

Bioethanol is a renewable alcohol made from plant materials—usually crops like wheat, corn, and sugar beet. When mixed with petrol, it reduces overall carbon emissions.

Why Did the UK Switch to E10?

The UK government introduced E10 in September 2021 to help meet climate targets:

• E10 produces fewer CO2 emissions than E5
• It's estimated to cut transport CO2 by 750,000 tonnes per year
• That's equivalent to taking 350,000 cars off the road
• It supports UK farming by using home-grown crops

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What Is E5 Petrol?

E5 is petrol with up to 5% bioethanol—half the amount in E10. Before September 2021, this was standard unleaded petrol in the UK.

Is E5 Still Available?

Yes! E5 is still sold at most petrol stations as "Super Unleaded" or "Premium Unleaded." It's typically 97 octane (compared to E10's 95 octane).

Look for these names at the pump:

• Shell V-Power Unleaded (E5)
• BP Ultimate Unleaded (E5)
• Esso Synergy Supreme+ (E5)
• Tesco 99 Super Unleaded (E5)
• Any petrol labelled "Super Unleaded" or "Premium Unleaded"

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E10 vs E5: The Key Differences

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Can Your Car Use E10?

Most cars built since 2011 are E10 compatible. But around 600,000 vehicles on UK roads today cannot safely use E10.

Cars That CAN Use E10

• Most petrol cars manufactured from 2011 onwards
• Many cars from 2000-2010 (varies by manufacturer)
• All new cars sold in the UK since 2011

Cars That May NOT Be Compatible

• Classic cars and vehicles over 20 years old
• Some cars from early 2000s (especially certain European models)
• Some older motorcycles and mopeds
• Certain lawnmowers, generators, and small engines

How to Check Your Car

1. Check inside your fuel flap—many have a label stating "E10" or "E5 only"
2. Check your owner's manual—it will specify compatible fuel types
3. Use the government checker—gov.uk/check-vehicle-e10-petrol

When in doubt, use E5 Super Unleaded. It's safe for ALL petrol cars, including those that can't use E10.

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What Happens If You Use the Wrong Fuel?

E10 in an E10-Compatible Car

Completely fine! This is what you should use.

E10 in a Non-Compatible Car (Occasionally)

A single tank of E10 in a non-compatible car won't cause immediate damage. You might notice slightly rougher running, but there's no need to panic. Just use E5 next time.

E10 in a Non-Compatible Car (Regularly)

This is where problems occur. Regular E10 use in an incompatible car can:

• Corrode rubber seals and hoses in the fuel system
• Damage fuel pumps and fuel lines
• Cause fuel injector problems
• Degrade certain plastics in older fuel systems

The higher ethanol content is corrosive to materials that weren't designed for it.

E5 in Any Car

E5 is safe for all petrol cars. If your car can use E10, using E5 is just fine—you'll just pay more.

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Does E10 Affect Fuel Economy?

Yes, slightly. E10 contains less energy per litre than E5 because ethanol has lower energy content than petrol.

What to Expect

• E10 gives approximately 1-2% worse fuel economy than E5
• On a 400-mile tank, you might get 392-396 miles instead
• Most drivers won't notice the difference day-to-day

Is E5 Worth the Extra Cost?

Let's do the maths:

• E10: £1.45/litre, gives 40 MPG
• E5: £1.60/litre, gives 40.5 MPG (1.25% better)

The E5 costs 15p more per litre but only gives 0.5 MPG better. E10 is still cheaper overall unless your car specifically needs E5.

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E10 and Classic Cars

If you own a classic or older car, pay close attention.

Why Classic Cars Can't Use E10

• Older fuel systems use materials that ethanol corrodes
• Rubber hoses, seals, and gaskets can degrade
• Carburettors weren't designed for high-ethanol fuel
• Fuel tanks may be susceptible to corrosion

Solutions for Classic Car Owners

1. Use E5 Super Unleaded—available at most stations
2. Look for ethanol-free fuel—some specialist stations sell it
3. Use fuel stabiliser—if the car sits unused for long periods
4. Consider fuel system upgrades—modern ethanol-resistant hoses and seals

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Finding E10 and E5 at the Pump

At UK petrol stations, you'll typically see:

The green pump handle is usually E10. Premium/super unleaded pumps are typically a different colour or clearly labelled.

Use our fuel finder to compare prices for both E10 and E5 near you.

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Common Questions About E10

Is E10 Bad for My Engine?

No—if your car is E10 compatible. Modern fuel systems are designed to handle 10% ethanol without issues.

Can I Mix E10 and E5?

Yes, absolutely. You can mix E10 and E5 in any ratio. Many drivers do this without problems.

Does E10 Go Off Faster?

Ethanol absorbs moisture, so E10 can degrade faster than E5 if left sitting for months. If your car isn't used regularly, consider fuel stabiliser or use E5.

Is E10 Cheaper Than E5?

Yes, typically 10-15p per litre cheaper. Despite the slightly worse fuel economy, E10 is still the more economical choice for compatible cars.

Will E10 Damage My Fuel Lines?

Only in older cars with fuel systems not designed for high-ethanol fuel. Cars manufactured after 2011 (and many earlier) have ethanol-resistant components.

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The Bottom Line

Here's what you need to know about E10 vs E5:

• E10 is now standard—it's the default "unleaded" at UK pumps
• Most modern cars are fine with E10—check if yours was made after 2011
• E5 is still available—look for Super Unleaded or Premium
• Older/classic cars should use E5—ethanol can damage old fuel systems
• E10 is cheaper—so use it if your car is compatible

Not sure which fuel your car needs? Check out our complete guide to choosing the right fuel, or use the government's E10 compatibility checker.

Ready to find cheap fuel near you? Try our free fuel finder.

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