You accidentally put the wrong fuel in your car…now what?

It happens to the best of us. In fact, research revealed that motorists fill up their car with the wrong fuel every two minutes. And let let’s be honest, it’s very easy to do – you’re in a rush, you’re late for work and you just want to fill your tank and be on your way. A momentary lapse in concentration, and it all comes undone – petrol in your diesel engine. Cue 30 minutes of quietly cursing yourself and you wonder how you could have been so unobservant.

But don’t panic, all is not lost.

You accidentally put the wrong fuel in your car…now what?

What happens when you put petrol in a diesel engine?

As well as powering the car, diesel acts as a lubrication oil that keeps the fuel pump and other components running smoothly. 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. Diesel is meant to self-light and therefore do not have spark plugs like petrol engines. Therefore, if you put the wrong type in and start the engine, it can cause damage to the fuel injector and other parts of the engine. 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. Petrol is made of a mixture that is designed to be stable and not set fire to itself – instead, the engine has a spark plug that sets fire to the petrol in order to start the car. Because diesel needs to be compressed before it’ll ignite, chances are you won’t even be able to start the engine.

What do you do now?

Whatever you do, 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 should do:
  • Tell the petrol station what’s happened.
  • Put the car in neutral.
  • 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. Treat this as you would a regular breakdown. With Matrix, you can rest assured that help is on the way with emergency roadside and medical assist*. Alert the Matrix control room of your emergency by pressing your panic button remote or call the control room, which is also available via one-touch dialing from your Matrix App.

*For MX3 customers only

Source: Automobile Association