What happens if you use the wrong fuel?

What happens if you use the wrong fuel?

Before we move on to anything else - if you’ve put the wrong type of fuel in your car, don’t switch the engine on or put the key in the ignition, especially if you’ve filled your diesel car with petrol. This will help contain the mixed fuel in the tank and stop it from circulating – which could cause permanent damage.

Topping up with the wrong type of fuel is an extremely common mistake to make; in fact, around 150,000 UK motorists find themselves in this predicament every year. There are a number of factors that affect exactly how much damage using the wrong fuel can cause – from how much fuel you’ve put in to whether it has circulated – so, while you won’t be able to undo what’s been done, you may be able to prevent further damage to your car by following the steps below.

What to do if you’ve put the wrong fuel in your car

If you’re still at the station:

  • Don’t start your engine or put the key in the ignition.
  • Put your car into neutral and ask someone to help you push it to a safe place.
  • Call a recovery vehicle and have them assess the damage.

If you’ve already started driving:

Unfortunately, at this point, the damage may have already been done; all you can do is pull over somewhere safe, remove the keys from the ignition, and call a recovery vehicle.

What happens if you put petrol in a diesel car?

Putting petrol in a diesel tank is far more common than vice-versa – mainly due to the fact that petrol nozzles fit easily into diesel tanks. Unfortunately, this is also the more costly mistake.

Diesel acts as a lubricant, and helps the fuel pump run effectively. Petrol, one the other hand, acts as a solvent when mixed with diesel, and has the complete opposite effect. The concoction will reduce lubrication and cause friction between parts, damaging both the pump and engine.

What happens if you put diesel in a petrol car?

Diesel pumps generally don’t fit in petrol tanks, so you’re far less likely to find yourself in this type of misfuelling situation.

While diesel needs to be compressed before ignition, petrol ignites through the spark plugs. This means that, more often than not, putting diesel in a petrol tank will result in your car not starting. Although not an ideal scenario, especially when you’re in a rush, this is a far less serious issue compared to the permanent damage caused by petrol in a diesel tank.

How to avoid putting the wrong fuel in your car

We all make mistakes, but there are ways to reduce the chances of misfuelling and save yourself a considerable amount of money, time and bother:

  • One of the most common times misfuelling occurs is when you’re filling up a new car that uses a different fuel to your previous one. It might be worth leaving yourself some form of reminder so that, if you find yourself reaching for the wrong pump out of instinct, you have a better chance of stopping yourself before it’s too late.
  • Always make sure you read the pump’s label before filling up.
  • Avoid distractions while filling up.
  • If you own a diesel car, it could an idea to invest in a diesel fuel cap that will prevent petrol nozzles from being able to fit in the tank. The price varies between make and model, but you can generally get hold of these for less than £30 – a small price to pay compared to a hefty repair bill.

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