It's a long story, but I have no documentation that asked for an oil change. I dropped my car off at a mechanic to get what I thought would be some routine work done. I asked for an oil change while I was there. After taking a look at it, they called me say they couldn't do anything and that I should take it to a body shop. I picked it up, paid nothing and got no receipt, and drove it to the body shop a few miles away. About halfway through, the oil light went on. Someone at the mechanic drained the oil for the change before they decided they couldn't do the repairs. The body shop confirmed that the tank was bone dry.
I should have turned right around as soon as the light came on, but I didn't. That was a big mistake.