What will happen If we use Petrol in Diesel Engine or Vise Versa?

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Are you planning to turn your garage into a laboratory, by adding diesel into patrol engine or patrol in a diesel engine? Well before you experiment with your vehicle’s engine, let me give a little clarity of conditions, which will surely arrive.


There are less chances of your engine to start and there or it will start but won’t last long, and finally, the engine will get a huge damage. Diesel engines are only suitable for diesel, whereas petrol engine works properly with petrol only.



Before discussing about conditions occur let take a quick look at some basic that will helps you to understand what will happen if we put petrol in diesel engine and vice versa.
petrol in diesel engine

Diesel engine:

There are lot of differences in the diesel and the petrol engines. Diesel engines basically works on diesel cycle. In a diesel engine, only air is induced in the combustion chamber via the suction pipe. The air in the combustion chamber is compressed by the piston. The compression ratio of the diesel engine is much higher than the petrol engine and the temperature if compressed air is increased at the end of compression due to the compression. Also, there is no carburation is present in the diesel. At the end of the compression stroke and at the beginning of the power stroke, a fuel injector atomizes the diesel and sprays it in the combustion chamber where compress air is present. When this spread diesel comes into contact with hot and compressed air, burning process of fuel begins and therefore the power stroke is obtained.

Petrol engine:

On the other hand, petrol engine works on the Otto cycle. In the petrol engine, carburetor prepares a homogeneous mixture of petrol and air, and this mixture is induced in the combustion chamber. Later in the combustion chamber, the piston compresses this mixture. At the end of compression stroke, the spark plug ignites this mixture and power stroke is obtained.The reason behind using the spark plug in the petrol engine is the auto igniting temperature of patrol and also its compression ratio. The auto igniting temperature of petrol is very high and on the other hand compression ratio of petrol engine is very low, this makes use of spark plug in igniting the fuel and air mixture.


For more information about these two engine read: Diesel Engine and Petrol Engine


Now, that we know, what these engines are and how they work. Now it will be easy for us to understand the outcome of using petrol in the diesel engine and vice versa.

If we use diesel in the petrol engine:

Well if you are going to use diesel in the petrol engine, then the suggestion is, not to do it. Diesel engines work on different principals than the petrol engines. It will surely not run and the reason behind it is the volatility of the diesel is lesser than the petrol. The carburetor cannot produce a fine vaporized mixture of air and diesel due to this low volatility. When this improper mixture reaches the combustion chamber, the spark is produced at the end of compression stroke but this spark won’t be able to produce enough heat to burn the remaining mixture of air and diesel and this will lead the engine misfunctioning and engine will not start.

If we use petrol in the diesel engine:

There will be some differences in the results if we use petrol in the diesel engines. Well, in this situation there are chances that the engine may start for a while but this will lead excessive damage to the engine. The fire point of diesel is greater than patrol and compression ratio of the diesel engine is also greater than petrol. At the end of the compression stroke the mixture of petrol and air is released into the combustion chamber, but unlike diesel, it burns immediately causing rapid burning of patrol. Due to this rapid burning detonation and knocking takes place. Piston starts to move to BDC before reaching the TDC during the compression stroke, this will reverse the engine and causes vibrations and noise in the engine. This will damage the engine and may turn it into a dead wood.


After examining both the situations, ie if we will add diesel to petrol engine or patrol to the diesel engine, we can say it is not a good idea experimenting with your vehicles engine life. In both the cases you will lose your engine or get it damaged badly and it not recommended either by the manufacturers or any motor specialists.  both the engines are designed to run only with a specific type of fuel.


Well, now I guess your plans of experimenting with you vehicles engines are changed, I suggest the use of appropriate fuel type for the long and healthy life of your white mustang’s engine life.

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