How to Drain Wrong Fuel from Your Car

Car Owl

Published in English •

Like (0)

Share

Share on X Share on Facebook Share on WhatsApp Share on Telegram Share on Reddit Share on LinkedIn Share via Email Copy Link

Summary

• Do not start the engine: If you've put wrong fuel in, starting the engine can cause serious damage.
• Call for help: A fuel drain service can fix the problem in about an hour.
• Cost: Expect to pay £150-£300 for a professional fuel drain.

Putting the wrong fuel in your car is more common than you think. Around 150,000 UK drivers do it every year. The good news? If you act quickly, you can avoid costly damage.

What to Do Immediately

The moment you realise you've put the wrong fuel in, follow these steps:

1. Stop fuelling: Don't add any more fuel.
2. Do not start the engine: This is the most important step. Starting the engine circulates the wrong fuel through the system.
3. Leave the car in neutral: Don't turn the key in the ignition at all.
4. Tell the petrol station staff: They deal with this regularly and can help.
5. Push the car to a safe spot: Get help to move it away from the pumps.

Petrol in a Diesel Car

This is the most common mistake. Petrol nozzles are smaller than diesel ones, so they fit easily into diesel tanks.

Petrol in a diesel engine causes serious problems:

• Petrol acts as a solvent and damages the fuel pump
• It reduces lubrication in the fuel system
• Metal components can grind together
• The fuel injectors can be damaged

Warning: If you've driven the car with petrol in a diesel tank, repair costs can reach £5,000 or more.

Diesel in a Petrol Car

This is less common because diesel nozzles are larger and don't fit easily into petrol tanks.

Diesel in a petrol engine is less damaging but still causes problems:

• The engine may misfire or run roughly
• You might see smoke from the exhaust
• The spark plugs can get clogged
• The catalytic converter may be affected

The good news is that diesel in petrol usually causes less permanent damage than petrol in diesel.

How a Fuel Drain Works

A professional fuel drain service will:

1. Pump out all the contaminated fuel
2. Flush the fuel system with clean fuel
3. Check for any damage
4. Refill with the correct fuel
5. Start and test the engine

The whole process takes about 30-60 minutes.

Cost of a Fuel Drain

Many breakdown services like the AA and RAC offer fuel drain as part of their cover or as an add-on.

Does Insurance Cover It?

Standard car insurance usually doesn't cover misfuelling. However:

• Some policies include misfuelling cover as standard
• You may have bought it as an add-on
• Your breakdown cover might include fuel drain

Check your policy documents or call your insurer to find out.

How to Prevent Misfuelling

• Stay focused at the pump: Don't use your phone while fuelling.
• Check the nozzle colour: Green is usually unleaded, black is diesel (but not always).
• Read the pump label: Always double-check before you squeeze.
• Fit a misfuel prevention device: Devices like a diesel filler cap blocker stop petrol nozzles fitting.

Misfuelling is stressful, but it's fixable if you act fast. The key is not to start the engine. Call a fuel drain service, and you'll be back on the road within an hour. For more tips on fuel and running costs, see our guide on what to do if you put the wrong fuel in your car.

Read our other articles: