What Happens If You Put The Wrong Fuel In The Wrong Car?

On the petrol station forecourt, amidst the oil tank installations are a range of different fuel nozzles that are made for a wide range of different cards.

There are usually several kinds of diesel, as well as E5 and more recently E10 petrol, and when making a quick fuel stop it is very easy to accidentally make a very costly mistake.

Misfuelling is where you refill your car with the wrong type of fuel for the engine type you have, most commonly by putting petrol into a diesel engine but occasionally by putting diesel into a petrol fuel tank, as well as pouring the recently required AdBlue additive into a fuel tank and vice versa.

It, in almost all circumstances, will do some damage to your car, but to what extent depends on which fuel ends up in which tank.

In any case, if you notice your error, do not turn the ignition key any further than it takes to unlock the steering wheel, call your breakdown provider and get your car to a safe place. If you do, not here is what you should expect to happen.

The least damaging scenario is putting diesel in a petrol car, in that, in most circumstances, it will not cause major lasting damage although it might be quite scary at first. As the thick diesel covers spark plugs and other important engine components the car may misfire badly.

It also may not start, or kick out a plume of nasty black smoke when it does, but once the tank has been drained and the right fuel put in, it should be fine in most circumstances.

Petrol in a diesel car, on the other hand, can cause significant and lasting damage to the engine, primarily because petrol, unlike diesel, does not act as a lubricant but a solvent to the engine.

This causes the diesel’s engine parts to rub against each other, causing damage, debris to block the fuel injector, and the petrol itself to damage some of the lining. If they get past the fuel filter and into the injectors, it can cause a misfire or even a seized engine.

This can be so expensive to fix that some insurers will simply write the vehicle off entirely.

Fuel in the AdBlue tank contaminates the system and often requires the entire system to be replaced.