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Bad gas in the car

Bad gas in the car. What are the symptoms of putting bad fuel in the tank

21 February 2017

If you fill the tank with wrong type of fuel, you can seriously damage the car and spend a lot of money on repairs. What are the symptoms of bad gas in the car?

How on earth can you misfuel at all?

Many people think it’s impossible to simply put wrong fuel in the tank of your own car. Surprisingly, though, misfuelling happens much more often than you would imagine. While there are no official statistics, a German automobileclub has recently made their own stats available; they claim there are approximately 20,000 cases of misfuelling each year. If Germans, who are so famous for being orderly and correct, do this on a mass scale, we can safely assume other nations – including ours – will most likely do the same at least just as often. Which drivers should be most careful not to misfuel, then?

You are at risk of misfuelling if your private car has a different engine than the car you use for work. If you are busy and tired and drive a petrol to and from work and a diesel while working, it is easy to forget which is which when you get to the station. Aggressive marketing of the fuel stations does not help, either; sometimes the names are so fancy you need to spend a while making sure which type of fuel you are looking at before you decide to purchase it. People also tend to misfuel rental cars; this happens quite often.


Pay attention

There is a common denominator in all the above cases: the driver does not pay adequate attention. If you often drive different cars and are too busy to always have time to check twice, one of the best ways to make sure you remember to pay attention is to learn the consequences of NOT doing so.


I have put diesel in a petrol tank. What can happen now?

This is much less dangerous for your car than putting petrol in a diesel tank but, sadly, it is also less common. Most fuel stations are equipped with a different nozzle for diesel and for petrol; the diesel nozzle is wider, so it is difficult not to notice it doesn’t fit. The difference in size won’t save you, though, if you are distracted and determined at the same time, or if you pour the fuel in from a canister.

What can happen if there is diesel instead of petrol in the tank? You can seriously damage the catalytic converter and oxygen sensors. Fortunately, the engine itself is quite likely to remain undamaged; it should simply stop as soon as you turn it on. If you only put a bit of diesel in the tank, you will notice atypical behaviour of the engine; it may start losing power or worsen its performance. Remember: if you notice such changes in the performance of your engine right after leaving the station, you should think twice before you continue driving.


I have put petrol in a diesel tank. What can happen now?

Unfortunately, this happens more often, and has more serious consequences than putting diesel in a petrol tank. Modern diesel engines are very dependent on the quality of fuel; feeding diesel into them may result in a real catastrophe. Diesel has a very important function: not only does it power the engine but it also lubricates the injection pump and injectors. Petrol has no such characteristics and as such, if you put it in the tank, it will cause pump and injector seizure. Mind you, replacement will be costly. Injector pumps and injectors can cost a few thousand. Additionally, petrol combined with air is more flammable than diesel, so you can also damage the piston-crank system. Once the pump, injectors and engine are all damaged, it may be cheaper to buy a new car than repair the one you have misfuelled!


Bad gas in the car. What do I do now?

First of all, as soon as you have realized the car is misfuelled, make sure you turn off the engine. You can call yourself lucky if you realize what has happened before you leave the fuel station. If the engine has not been turned on yet, it is best to react immediately. Inform one of their assistants of the situation before you do anything else. Some fuel stations have professional equipment used to pump the wrong fuel out of the engine. It yours does not, you should call roadside assistance to have the car hauled away to a professional repairs station where the fuel can be removed, the system cleaned and the filters replaced.

It is good to know

We strongly recommend that you do not try to drive to the repairs station on your own.



If you have a diesel car, this is out of the question. A car with a compression-ignition engine will let you drive up to a few hundred kilometres when filled with petrol, although damage will already be there when you start it. Diesel engines are much more durable, though; they will often work until the very end so your car will only stop when damage is beyond repair. If you only put a bit of diesel in a petrol tank, then theoretically speaking, you could drive to the mechanic but why should you save the 100 or 200 PLN on hauling when potential damage caused by your driving the car with wrong fuel may be much more expensive to repair?


Misfuelling does not have to be your fault at all!

Every year, the Polish UOKiK (Office of Competition and Consumer Protection) controls fuel quality in different stations. Results of their control prove that you may misfuel the car despite making sure you have asked for the right type of fuel. In such cases, the type of fuel will be correct, of course, but the quality will be very poor. It is always a good idea to make yourself familiar with the data UOKiK makes available and make sure the station you use most often does not appear in their reports. Regular use of low quality fuel may cause damage to the engine, too!


It is good to know

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Bad gas in the car. What are the symptoms of putting bad fuel in the tank
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Bad gas in the car. What are the symptoms of putting bad fuel in the tank
If you fill the tank with wrong type of fuel, you can seriously damage the car and spend a lot of money on repairs. What are the symptoms of bad gas in the car?
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