Over years of working in a mechanic shop and shopping Craigslist, I’ve noticed here and there that people will claim that their old car is still equipped with its original factory-installed fuel pump or fan belt or water pump or whatever, despite the vehicle’s high mileage. “Pulled the brakes apart today. The car is still using the original brake rotors.”

Usually this is 3 or 4 owners in.

Unless they have access to every service record from day one, and know that they aren’t missing any, how do they know that it’s an original part? Do they just see dealer-installed OEM parts and assume they’re the original ones? Kinda confused here. Maybe I’m missing something obvious.