Engines work by making explosions, lots and lots of explosions. That sound you hear when the car is idling? That’s 20 or so explosions every second.
These explosions have to be rather precise, and happen at a certain pace. This is achieved in different ways depending on the type of engine, a gasoline engine will ignite the fuel at the right moment using spark plugs, while a diesel engine will compress the fuel until it ignites on its own.
Using the wrong type of fuel will simply cause the explosions to happen at the wrong times (or not at all), and thus screw up the pace.
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