Though they both start off as oil, the properties of diesel and gasoline diverge quite a bit after that. One relies on compression to do the job, while the other relies on compression and spark. All of this would be well and good, except that the pumps which feed these fuels into our cars and trucks often look very similar. Consequently, it happens that people fill their ride up with the wrong fuel and do enormous amounts of damage to the engine and fueling system.

Host Jon Bentley holds up the gasoline (left) and diesel (right) fuel dispensers to show how easy it is to confuse them.

The Great Britain-based YouTube channel, Fifth Gear, sought to find out what happens when these fuels intermix and go in the wrong type of vehicle – a mistake known as “misfueling.” This mistake, which happens tens of thousands of times a year in the U.K. (imagine how common that must be for the U.S.), costs a great deal to fix, from replacing much of the valvetrain to straight-up requiring an all-new powertrain.

Bentley starts with a Ford Escort, a compact sedan that runs on gasoline. With a practically empty tank, he pours in five liters of diesel and proceeds to start the car, which it surprisingly does. The car proceeds to operate normally for a few minutes, until severe vibrations begin to rattle the car. Bentley siphons out the diesel to the best of his ability and refills the car with gasoline, in the hopes of restoring the car to normal operation and having it pass an emissions test. Amazingly, the car passes with flying colors.

The Ford Escort was back to its normal self once it was refilled with gasoline.

The same results didn’t carry over so well with the diesel car, however. This one was a hatchback Vauxhall Astra. It started up and drove for the same time as the Escort, and Bentley claimed to feel a bit more perkiness to the car’s step, too. But during the emissions test, the car sputtered and died and wouldn’t start again until it was refilled with diesel. Once restored to its proper fuel, the car started up and carried on like a champ.

The moral of the story, if there is one, is to make sure you always check the pump before you fill up. Otherwise, you’re due for a world of hurt, both to your vehicle and your finances.

Sparks spit out of the diesel -powered Astra during the emissions test.