Skip to content

Misfuelling cover

Misfuelling: What to do when you use the wrong fuel

Sara Newell
Written by  Sara Newell
5 min read
Updated: 14 Feb 2024

Putting the wrong type of fuel in your car is surprisingly common – and you can cover yourself against it.

Misfuelling might not be a term you're familiar with until the moment you're standing at the petrol station, realising you've just filled your diesel car with petrol, or vice versa. It's a simple mistake, but one that can lead to a cascade of engine troubles if not handled correctly. In this guide, we'll walk you through the steps to mitigate the damage and get back on the road safely.

Understanding misfuelling

Misfuelling is exactly what it sounds like: accidentally putting the wrong type of fuel in your vehicle. It's surprisingly easy to do, especially if you're in a rush or distracted. Despite being a common blunder, with the RAC reporting around 150,000 incidents in the UK each year, the consequences can be severe.

The immediate response

If you catch your mistake while still at the pump, the most crucial thing to remember is do not start your car. Doing so can cause significant damage to your engine. Instead, follow these steps:

  1. Remove the key from the ignition to ensure the engine doesn't engage.

  2. If possible, push your car to a safe spot or ask the station staff for assistance.

  3. Before taking any further action, it's essential to check your insurance documents to see if you have breakdown cover or misfuelling cover.

  4. If you're covered, get in touch with your insurer right away.

  5. If you're not covered, you'll need to call a breakdown service. Be aware that this may come with a fee if you're not already a member.

If you've already driven away from the petrol station, find a safe place to pull over as soon as possible and turn the engine off. Put the car into neutral and move it somewhere safe if you can.

Refuelling a car

The consequences of misfuelling

Petrol in a diesel car

This is the more problematic scenario. Diesel engines rely on the fuel's lubricating properties, which petrol lacks. If petrol is introduced to a diesel engine, it can cause friction and damage to components like fuel lines and pumps. Symptoms of misfuelling a diesel car with petrol include unusual engine noises, smoke, reduced acceleration, and potential engine cut-outs. Repairs for misfuelling, especially when petrol is put into a diesel car, are normally expensive and may require replacing the whole fuel system.

Diesel in a petrol car

While not as severe, putting diesel in a petrol car can still lead to trouble. Diesel can clog spark plugs and disrupt the fuel system. You might notice smoke and a struggling engine if this happens.

E10 fuel and misfuelling

Introduced in Great Britain in September 2021 and Northern Ireland in early 2023, E10 fuel contains up to 10% ethanol, compared to the 5% in the previous standard E5. This change aims to reduce carbon dioxide emissions from petrol vehicles. The government estimates that 95% of petrol-powered vehicles can run on E10 petrol. Most cars manufactured since 2011 should be compatible with E10, and many older vehicles are as well. However, there are exceptions, including classic cars, certain makes and models, and mopeds. For these vehicles, 'super' grade petrol, which remains at E5, is recommended.

If you're unsure whether your car can handle E10, the government provides a tool that lets you check if your vehicle can use E10 fuel. Using E10 in an incompatible vehicle could lead to long-term damage, so it's worth checking before you fill up.

Insurance and misfuelling

When it comes to insurance, some policies include misfuelling cover as standard, while others offer it as an optional extra, and some insurers do not offer misfuelling cover at all. A robust misfuelling policy should cover the cost of draining and cleaning the fuel tank and reimburse you for the contaminated fuel. However, be aware of any limitations, such as how far you've driven with the wrong fuel in your tank.

Finding the right misfuelling cover

The best way to get a good deal on misfuelling cover is to compare car insurance using MoneySuperMarket. By providing your personal and vehicle information and specifying the need for misfuelling cover, you can receive tailored policy comparisons.

Misfuelling is a mistake that can happen to anyone, but with the right knowledge and immediate action, you can prevent a bad situation from getting worse. Remember to stay calm, don't start the engine, and check your insurance coverage. With these steps, you'll navigate the issue with as little disruption as possible.

Looking for car insurance?
Start a quote