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Petrol in Diesel Engine and Diesel in Petrol Engine

Updated: Nov 5, 2023

Sometimes we get a question about what would happen if one mistakenly fills petrol in a diesel engine or vice versa. Is it even possible to replace each other? Will they damage the engine or just run as smoothly as before? Let's find it out.

Diesel in Petrol Engine

One can not fill diesel in petrol engine because nozzle that is used for diesel is bigger than filler neck of the petrol tank.

Even if somehow you fill diesel in petrol engine spark plug won't be able to ignite diesel and the engine won't start because diesel is more oily and heavier than and diesel does not evaporate like petrol as it is less volatile.

Petrol in Diesel Engine (High Risk)

If by mistake one fills petrol in the diesel engine damage will happen for sure. Petrol is volatile, hence, if one tries to start the engine it would lead to detonation as the compression ratio in diesel engines is almost twice as high as in petrol engines.

Also, diesel acts as a lubricating oil hence if petrol is added to it, it will lose its lubricating property and wear the engine parts in a short period of time.

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