When you open your fuel filler door, you may miss that bright green letter D staring you in the face. That D stands for diesel, and it's what your engine craves. If you put regular gasoline in there, you're going to have a bad time. What exactly happens when you put gas into a diesel vehicle's fuel tank? Our friend Jason Fenske from Engineering Explained is here to explain things.

For this video, our faithful host is joined by another YouTube creator. He's Charles Sanville, the Humble Mechanic, and he brings a decade-plus of knowledge and experience as an automotive service technician into this video. The pair sit down and dive right on in to what happens you put gas into a diesel tank.

ALSO SEE: Five things you should never do with a 4x4 vehicle

You're dealing with a lot of components that deliver fuel into the engine, so there are many parts that need to be examined. Some just need to be flushed and cleaned out, while others need to be replaced. Additionally, there's a special disposal process for the combined gas-diesel fluid you've just created, and it's surprisingly expensive. That cost, along with the parts and labor to fix your diesel car, will run somewhere between $5,000 and $8,000, at least for a VW diesel. Expect higher end diesels from Mercedes-Benz and BMW to cost even more to fix.

The best way to avoid all of this? Pay attention to what you're doing. Automakers are making it tougher to accidentally pump the wrong fuel by using different size fuel filler necks, but you should still focus on the task in front of you...even if it's as mundane as filling up your tank.


Follow Motor Authority on FacebookTwitter and YouTube.