Why you should never put diesel in a petrol-powered engine
What's the story
In a bizarre incident, a dealership wrongly filled a petrol-powered Mahindra XUV700 with diesel fuel before delivering the SUV to its owner. After realizing their mistake, the dealership tried to fix the issue by draining the fuel tank and cleaning it thoroughly, before handing over the car. So what exactly happens if you fill a petrol-engined vehicle with diesel?
Context
Why does this story matter?
Traditionally, Internal Combustion Engines (ICE) are fueled by either petrol or diesel for propulsion. While both have an overall similar effect, the method used for the combustion of both fuels is as different as day and night. While it is not advised to run the wrong fuel in your car, sometimes such things can happen accidentally.
Working
Firstly, a quick look at how petrol engines work
To generate power, a petrol engine uses an efficient four-stroke cycle to burn petrol within the engine's cylinders. The fuel is injected into either the intake manifold or the combustion chamber, where it is combined with air to provide an optimal combustion effect. The rich air-fuel mixture is then ignited by the spark from a spark plug, which helps rotate the crankshaft.
Information
How does petrol differ from diesel?
Petrol and diesel differ in chemical composition, ignition method, combustion characteristics, and energy density. Petrol uses spark ignition, has lower flash point, and lower energy density. In comparison, diesel uses compression ignition, has higher ignition point, and higher energy density.
Effect
What will happen when petrol car is filled with diesel?
It is difficult to end up with diesel in a petrol car due to the larger nozzle size. However, if incorrect fuelling ever happens, the fuel filter/line will clog up as petrol engines are not designed to cope with the overall thickness and greasy properties of diesel. Also, with its higher ignition point, the fuel will not burn, resulting in flooded engine cylinders.
Remedy
What can be done in such situations?
If you fill diesel for less than 5% of the total tank capacity, all you need to do is fill the rest of the tank with petrol. As diesel easily mixes with petrol, you can continue driving to the nearest service center. If it is more than 5%, we recommend shutting the car down immediately and opting for towing services or Road-Side-Assistance (RSA) service.