What to Do If You Put the Wrong Fuel in Your Car

Written by John

On December 15, 2020
wrong fuel in your car

When you have a fleet of cars, you may change them every few years. You take in the feeling of the vehicle and that new vehicle smell. But what happens when you set off and see you need to top up? Or, as we are getting EV’s now, where is the charge point? What if you put the wrong fuel in?

Important: If you’ve used the wrong fuel, do not switch on the engine or put the key in the ignition.

There are now new labels on the fuel pumps. This is to make it clear which fuel you should be using in your car. There is no change in the fuel itself, just the labels.

Ironically, this may cause even more confusion in the short term as motorists are used to seeing ‘unleaded’ and ‘diesel.’ Instead, they are now greeted with ‘E5’ and ‘B7’. It may just happen that you choose the wrong pump and accidentally put diesel in your petrol engine. But worry not – there’s a way out of this.

New Petrol and Diesel Pump Labels Explained

The new labels are designed to tell you exactly what you’re putting into your car. First is the shape on the label: a circle means petrol, and a square means diesel.

The letter on the label tells you what renewable fuel source has been added to help with the environment: E means ethanol, and B means biodiesel.

Finally, the number tells you what percentage of that renewable fuel is mixed in. E5 means your petrol is made up of 5% ethanol, and B7 means your diesel is made of 7% biodiesel.

As well as fuel pumps, the government plans to have these labels put on the fuel caps of cars from April 2020.

What Happens When You Put Petrol in A Diesel Engine?

Not only is diesel powering your car or van along, diesel acts as a lubricant oil that keeps the fuel pump and other components running smoothly. If you were to add petrol acting as a solvent when mixed with diesel has the opposite effect. Adding petrol to a Diesel engine increases friction between parts, causing damage to the fuel lines and pump. If you drive away or even start the car with petrol in the mix, you could cause expensive damage to the engine.

What Happens When You Put Diesel in A Petrol Engine?

Diesel pump nozzles tend to be larger than most petrol fuel necks, so misfuelling in a petrol car doesn’t happen all that often. Luckily, putting diesel in a petrol engine isn’t as bad as the other way around. Because diesel needs to be compressed before it’ll ignite, chances are you won’t even be able to start the engine.

What to Do If You’ve Put the Wrong Fuel in Your Car

First of all, and this is most important: Do not start your engine. Don’t even put the key in the ignition.

If you’ve realised your mistake before starting the engine, here’s what you do:

  • Tell the petrol station what’s happened.
  • Put the car in neutral.
  • Have someone help push your car to a safe place.
  • Call your insurer as soon as you can.
  • If you have breakdown cover, give them a call – they should be able to drain, flush and refuel your car.

If you aren’t so lucky and you drive off with the wrong fuel, you’ll soon realise what’s happened when the car grinds to a halt.

If you have breakdown cover, some policies will take you to the nearest garage or home. Some may be an extra charge for draining the tank. Some may have it as an add-on when getting your breakdown cover, so check with them.

Some insurers do not cover misfuelling as standard so check with them when arranging your policy. However, any resulting damage to the engine may not be covered. In any case, it’s best to check the small print of your policy to make sure.

How to Avoid Putting the Wrong Fuel in Your Car

The obvious answer here is to be attentive while filling up, but that’s sometimes easier said than done. An alternative way to prevent this from happening is by fitting a diesel fuel cap to your fuel neck. This cap stops petrol nozzles from fitting into fuel tanks they’re not meant for.

These caps are designed to fit into specific makes and models, so be careful you choose the right one. Depending on your model, they tend to cost between £15 and £30.

You could get a sticker and put it on the inside of the fuel cap door. You could even get a keyring saying diesel or petrol on it. Try using a petrol station that is close to home, and going to the same pump all the time. This gets you into the habit of choosing the right one.

For more information or a free consultation, get in touch via our website or email john@parrysfleetservices.co.uk

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