This one my son did when he was a teenager. We bought him an older Toyota Cellica as a first car. It was high mileage and used oil so he had to check oil often. He came home one day and said he had oil all over his hood and it had been that way a couple day. Of course there was lecturing involved about driving it so long and not checking blah blah.
I went out popped the hood and there was the oil cap laying in a crevice on the engine. No oil on the dipstick. Car was making a lot of engine noise after. I decided to have a mechanic look at so about a week later we took it to a mechanic and the mechanic called and said the oil cap had been left off, he found it on the engine. I said, "what yeah that was what happened to it to begin with." He said it was laying on their just now when he opened the hood. My son had forgotten AGAIN to put the oil cap on.
The car was not drivable, had a lot of knocking and I sold if for $500 to an elderly man knowing what had happened to it and he still bought it. I had tried different additives but nothing seemed to work.
The other day we were finishing an oil change on his 2017 Rogue and he said wait, before we closed the hood, I have to touch the oil cap before I can close the hood, LOL! Expensive lesson for him.