An epic thread at r/AskReddit invites mechanics to describe the dumbest things people do to their cars.
As you can imagine, there is some pretty stiff competition. Here’s a quick tl;dr of the 7000-comment thread.
1. Neglect to check the air pressure of the spare tire. — Back2Bach
2. Neglecting regular car washes in the winter cuts the life of your car in half. – gauget
3. Don’t “literally top off” your oil. – Fingerbangbandit
4. Use “placebo bullshit devices [such as] magnets on the fuel line to “align” the gas [and] strange metal fins in the filter housing to spin the air. – rdesktop7
5. Add decals or badges from fast cars that are not even from the same manufacturer – various. (cf. leave dealership stickers on their cars – Kranenborg )
6. Ride on bald tires. – Ravenwald (who has other good ones, too).
7. “Put that loud fucking exhaust on their car and think they have the fastest car on the block. Bitch your shit sounds like a lawnmower” – BattlingMink28
8. Any modification that costs more than the vehicle is worth – huhaskldasdpo.
9. Do nothing when the check engine light comes on. – indymash.
10. “Pretty much every aftermarket part” — Sneeze_wee, who claims to work in auto insurance and has more.
Guilty of #2. Guilty of #8, too, but that’s just because the rubber cement used to glue a window seal back on is worth more than a ’99 Nissan Sentra.