I'm with you on the "free" dealer oil changes. I had four with my '14 Silverado, and I only managed to use one.
On that visit they did an overfill. When I called them on it they tried to say I wasn't checking the oil properly. Funny, I didn't think it took a PhD to check oil level, in fact a "dipstick" can do it. If they'd owned their mistake I wouldn't have been so P'd off instead they tried to say I didn't know how to read a dipstick. WRONG ANSWER
Long story, as GM and their dealers didn't know how much oil it took for one of its designed engines, they put the "correct" 8.5 quarts in along with the lovely PF63E ecore
filter. I removed their filter and its oil and replaced with a Wix 57045. The oil in the filter I removed was almost exactly enough to bring the oil level down to the full mark on the dipstick.
I believe that is how you read it, but my dealer might disagree.
Anyway, like most here say, if you want something done right do it yourself. I've done two oil changes since the dealer visit. No drama, no overfill, no ecore, full synthetic oil; sometimes "free" has a hidden price and I am not willing to pay that price anymore.