Every three and a half minutes of every day, someone at a UK fuel pump has that sinking feeling as they realised they’ve grabbed the wrong nozzle, and have either put diesel in their petrol car or pumped petrol into the diesel tank.

We’ve all either done it, watched someone else do it, or have just managed to catch ourselves in time before disaster strikes. Some car breakdown companies even offer ‘Wrong Fuel Cover’, it happens that often.

So if you have got your green and black nozzles mixed up and put the wrong fuel in your car, what should you do?

1. Don’t start the engine

As soon as you start your engine (and that even includes simply turning the ignition system on), your engine starts to pump fuel around. And the deeper the wrong fuel goes into an engine, the more damage it can cause. If you’ve realised your mistake at a petrol station, simply push the car away from the pump (most forecourts have some room at the side for vehicles to park), and call your breakdown company. They will then come out and drain your tank for you so that you don’t distribute the fuel around the engine.

As this is regarded as an ‘Avoidable incident’ by breakdown companies, expect to be charged, unless you have wrong fuel cover and have paid an excess. And unless you’re a lone female, don’t expect to get priority treatment either – it’ll be a bit of a wait before the breakdown service turns up.

2. Too late!

Sometimes, you don’t realise you’ve put the wrong fuel into your car until it’s too late. You may get a few miles down the road before the car coughs and dies. At this point, don’t try to restart the car, as it will only cause even more damage. It’s time to call out the breakdown service and get your car towed home or to the nearest repair centre.

Why is it such a big deal? Surely fuel is fuel?

Petrol and diesel have very different chemical compositions. Diesel is a lubricant, whereas petrol is a solvent, which means that once it gets into a diesel engine it can do some damage, especially in newer diesel cars. These are known as Common rail (or HDi) diesel engines, and petrol in these can cause serious damage to the fuel injectors, pumps, pipes, and filters.

In older diesel cars (over 20 years old), a very small amount of petrol may not cause as much catastrophic damage (in fact, Volvo recommend that a very small amount is added during the winter to prevent the diesel from emulsifying and thickening, although this is probably only relevant to drivers living in Sweden, and certainly not recommended by other manufacturers!). But it can still make the engine run very badly, and you’ll find the car especially difficult to start.

The best advice is to always err on the side of caution, regardless of the age of your car, and if you’ve put the wrong fuel in, don’t start the engine.

How could I have been so stupid?

Don’t beat yourself up too much, it’s an easy mistake to make, especially if you have a diesel car. The petrol nozzle on a pump is slightly smaller than the diesel nozzle (which is why it’s difficult to misfuel a petrol car), and when you’re in a hurry it can be all too easy to grab the wrong pump without checking first.

Every year, around 150,000 drivers make the same mistake, often when they’re driving hire cars they’re not familiar with, or have just changed cars.

A costly mistake

If you do put the wrong fuel in, then if you get off ‘lightly’ and have the tank drained by your breakdown service, then you’ll lose the cost of your fuel, and probably a fee for draining the tank, which you may be able to claim back if you have wrong fuel insurance cover. However, if you have to have the vehicle towed to a garage after running the wrong fuel around the engine, the cost could run into four figures. If your car is older the insurance company may even regard your vehicle as a write-off, and scrap it, rather than pay out for replacement engine parts.

You will need to let your insurance company know if repairs are needed, especially if you have Wrong Fuel Cover on your policy. Another additional cost further down the line is that a claim for misfuelling your car could invalidate your no-claims bonus, and send your premiums up next time you insure your car.

So if you want to avoid a very expensive trip to the petrol station, take extra care every time you stop for fuel. Make sure your fuel cap has a clear sticker inside indicating whether your vehicle takes diesel or petrol and double check which nozzle you’ve picked up before you press the start button.

Need Misfuel Insurance?  Get in touch now on 0800 917 9522.