Koolau
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Not nearly as bad as this, but a friend had his girlfriend add motor oil to the automatic trans instead of the engine. It was only 1 quart, and he did a drain and refill, but after having the vehicle driven a bit. Of course that doesn't get rid of all of it unless you do a full power flush. But it diluted enough that it seemed to have no bad effect. After all automatic transmission fluid is really more a hydraulic pressure fluid than pure lubricant. This was also back with traditional hydraulic valve body automatic, not the new electronic solenoid controlled like current cars. Plus both motor oil and ATF are petroleum based so they mix fine. Not like oil and water for sure.
The family business had an old GMC that was burning oil something fierce. I ran out of oil for it and put in some transmission fluid. The sound of the engine smoothed right out and the smoke was lessened. Not sure how good the actual lubrication was, but since the vehicle was just barely worth keeping, I didn't worry about it. I WOULD worry about motor oil in the tranny, however. Glad you saw no damage.