Quick Guide to Misfuelling

‘Misfuelling’ is the term used for putting the wrong type of fuel into your car. If this happens to you, you are not alone: thousands of Brits make this mistake every year! Although it is a common mistake, it can be an expensive one, especially if you have started your engine with the wrong fuel in the tank. The best way to avoid this mix up is to always pay attention at the pump, particularly if you are driving a new or different car. If you do mis-fuel your car, follow the advice we have collated below on what to do next.

What to do if you’ve misfuelled

You have just filled up at the petrol station and you realised you have put the wrong fuel in your car. What now? Hopefully, you have not started your engine, as this will allow fuel to circulate the tank and cause damage to the engine. If you have realised your mistake before turning on the engine, there are two key steps to take:

Firstly, put your car in neutral and push it into a safe place in the petrol station forecourt, out of the way of other vehicles. Station staff can help you put your car in the right spot if you are unsure of where to go.
If your insurance covers mis-fuelling, contact your provider, who will be able to send a recovery team to take you to a garage. This will count as a claim, but your insurers can offer you discounted misfuelling services. If your insurance does not cover you for mis-fuelling, petrol station staff can let you know who is best to contact.

If you started your car before realising you have misfuelled, pull over and stop your car in a safe place. Turn off the engine and contact your insurance or misfueller provider. Unfortunately, you will have a more expensive bill to fix the damage, but any damage is usually fixable at a garage.

Petrol in a diesel car

Petrol acts as a solvent, reducing lubrication in the engine, which can damage the fuel pump and other engine parts in a diesel car.

A small amount of petrol (less than 5 litres) usually won’t do significant damage to a diesel car. Unless advised otherwise by your insurance provider or car manufacturer, you can top up with diesel and continue as usual. Always check with a professional on how best to proceed, no matter how much of the wrong fuel you have put in your car.

If there is more than 5 litres of petrol in your diesel car, you will need help to fix the problem. At a garage, you will either need your car drained and the parts cleaned, or parts may need to be replaced if you have driven your car with the wrong fuel. The cleaning of parts is the cheaper option, yet you may not have a choice but to replace parts if they are too damaged. That is why it is always better to keep your vehicle’s engine off if your mis-fuel.

Diesel in a petrol car

It is much rarer for diesel to be put into a petrol car, due to the size of the diesel nozzle being incompatible with the petrol car. It is also less damaging than putting petrol in a diesel car.

If it does happen, and more than 5 litres of diesel is put in, the diesel won’t ignite the spark plug like petrol does, so the car won’t start. The car will need to be drained and have its fuel replaced.

However, if there is less than 5 litres of diesel put into the wrong car, it can still function if you top it up with petrol, although the exhaust may be smoky and the car feel different to drive. In any instance of mis-fuelling, check with a professional on the best next steps to take.

Claiming on your insurance

If you start your engine after misfuelling, you will have to take your car to the garage, where it will be drained and the parts cleaned or replaced. This could include parts of the engine or the whole engine, and replacement is most likely if you have driven with the wrong fuel in your car.

Some insurance will cover the replacement cost under accidental damages. Check your policy to see what you are covered for so that you know what insurance help you can expect if you mis-fuel your vehicle.

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