What Happens if You Put Diesel in a Petrol Engine Car?

In the event that you put diesel fuel in a petrol engine car, it can cause significant damage to your vehicle. This mistake is quite common and can happen to anyone, especially those who are not familiar with different types of fuels and engines.

Background Information

To better understand the consequences of putting diesel in a petrol engine car, it is important to know the basic differences between these two fuels.

  • Petrol, also known as gasoline, is a highly flammable liquid made from petroleum. It is designed to be used in spark-ignition engines found in most cars.
  • Diesel, on the other hand, is a type of fuel that is less flammable than petrol and is commonly used in diesel engines, which are found in heavy-duty vehicles such as trucks and buses.

Consequences of Putting Diesel in a Petrol Engine Car

Now that we have a basic understanding of the two fuels, let’s discuss what can happen if you accidentally put diesel in your petrol engine car.

  • The most obvious issue is that your car will not start. This is because diesel fuel requires different conditions to ignite compared to petrol, and the spark plugs in a petrol engine cannot produce enough heat to ignite the diesel.
  • If you do manage to start your car, it will likely run poorly and eventually stall. Diesel fuel has a higher viscosity than petrol, which means it cannot be properly atomised by the fuel injectors in a petrol engine. This can lead to clogged fuel injectors and reduce engine performance.
  • The diesel fuel can also damage the components of your car’s fuel system, such as the fuel pump and fuel lines. Diesel has a solvent effect, meaning it can break down certain materials used in petrol engines, causing them to deteriorate or fail.

What to Do if You Put Diesel in a Petrol Engine Car

If you accidentally put diesel in your petrol engine car, the first thing to do is not panic. Here are some steps to help mitigate the damage and get your car back on the road:

  1. Stop driving immediately: As soon as you realise your mistake, pull over safely and turn off the engine.
  2. Drain the fuel tank: The best solution is to have a professional mechanic drain the fuel tank completely and clean it out thoroughly.
  3. Replace the fuel filter: Diesel can leave residue in your car’s fuel system, so it’s important to replace the fuel filter to prevent any further damage.
  4. Check for other damages: Have a mechanic inspect your car for any potential damage caused by the diesel fuel. This may include the fuel pump, injectors, and other components.

What to Do with a Damaged Petrol Engine Car

In some cases, the damage caused by putting diesel in a petrol engine car can be too severe or costly to repair. This is where companies that offer cash for cars come in handy. These companies specialise in buying damaged cars for sale in Melbourne, regardless of their condition. They can offer you a fair price for your car and handle the disposal process for you.


Putting diesel in a petrol engine car is a costly mistake that can cause extensive damage to your vehicle. If this happens to you, it’s important to remain calm and take immediate action by draining the fuel tank and having your car inspected by a professional mechanic. If the damage is too severe, consider selling your car to a company that offers cash for cars in Melbourne. This way, you can at least recoup some of the costs and avoid further headaches.  So, always make sure to double-check before filling up your tank!