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What happens to car if you fill it with wrong fuel

What happens to car if you fill it with wrong fuel Illustrative photo (Freepik)
Author: Maria Kholina

It seemed like such mistakes could only be made by novice drivers, but in reality, that's not the case. Global statistics show that thousands of people each year accidentally fill their cars with the wrong fuel, and that can be dangerous for the vehicle, according to Total energies.

Difference between gasoline and diesel

These two types of fuel have the same purpose, but their methods of achieving it differ. Gasoline requires a liquid mixture and a spark to initiate the combustion process. It doesn't withstand high pressure.

Unlike gasoline, diesel requires a high level of compression to self-ignite without using a spark. This means that if you strike a match and throw it into a tank filled with diesel fuel, nothing will happen (it's not advisable to test this in practice) because the lit match doesn't have the capability to ignite the fuel enough to cause combustion.

What happens if you put gasoline in a diesel car

Gasoline can cause more harm to a diesel car than vice versa. Even small amounts of gasoline can wash away the thin film that lubricates the diesel fuel injection pump. The problem arises because the lubricating properties of gasoline differ from diesel.

Gasoline is more volatile than diesel fuel, meaning that if it gets into the tank of a diesel car, it will ignite faster, causing ignition misfires, spluttering, detonation, engine power loss, and potentially irreversible engine damage.

Burning gasoline in any diesel engine will almost certainly result in irreparable engine damage.

What happens if you put diesel in a gasoline car

Putting diesel in a gasoline car is more difficult than the other way around because the diesel fuel nozzle doesn't fit into the opening of gasoline car tanks, which serves as a certain protection, but older car models may not have this.

Even a mixture containing only 5% diesel fuel can cause significant damage to a gasoline engine and its catalytic converter if you've been driving the car for a prolonged period during which ignition misfires and spluttering occur.

Theoretically, diesel fuel should not ignite in an engine running on gasoline because it doesn't vaporize like gasoline. Gasoline engines are not designed to burn diesel fuel. This means that if your car runs out of gasoline, the engine will stall, even if you previously added diesel fuel.

What to do if you make a mistake

First of all, you should turn off the engine without trying to restart it. This increases the likelihood that the incorrect fuel will remain in the tank, where it can cause less damage.

Some car models begin mixing fuel before you start the engine, so don't insert the key into the ignition if you realize you've made a mistake with the fuel.

Call a tow truck to take you to a professional auto service where they will drain the fuel from both the fuel system and the tank. After that, the fuel tank will need to be disassembled and thoroughly cleaned. Only then, if everything is okay, can you properly refuel the car and drive it.