In December of 1987, I bought an '88 Mercury Cougar. The dealer had a policy that every new car purchased would get "free" oil changes for the life of the car. I tried to knock the price down by saying that I do all oil changes myself, but the dealer wouldn't budge and said that it was company policy. ALL new cars sold there got the free oil changes.
At the time, I was living in an apartment complex, unable to do oil changes myself, so I took it to the dealer for the first oil change.
Well, THE VERY FIRST OIL CHANGE THAT THEY PERFORMED, I get the car back to my apartment complex and I soon see a big oil puddle underneath my car. They had stripped the oil plug. How incompetent could they be? I take it to the dealer and they drop the oil in a dirty bucket, put in a new plug, and then put the old oil back in my car.
I never took my car back there again to have a service performed. I actually did all of my oil changes after that, even if I did have to pay for them.