There are some dealers that will do things right and some that do it on the cheap. The higher end brands (luxury brand dealers) from larger dealer networks tend to do things right. I used to work for Infiniti , Porsche, and Audi as a mechanic. We always sought to use the right parts and if we couldn't get them we'd order them. Be it oil or brake rotors for a used vehicle refurbish. Non luxury lines like Chevy and Ford it'll depend on how they're run. Independent dealers it's a toss up.