At a dealer oil changes are done by beginners.....usually part time so the cost to the dealer very little. Started to drive off in my Mazda years ago from oil change but oil light would not go off so I did not even leave the lot. Shut it down and found no oil and no drain plug. I only got to a dealer for warranty work as we have no choice. And that I hate...half ass work I had to redo and hooned my car for days on my only visit!