I acquired a 1989 740 GL with auto trans a while ago. It was obvious that the trans fluid had not been frequently changed, so I drained it, and after checking with the owner's manual, added about 7 qts of Dexron. This seemed like a lot, but that's what the manual said.

This resulted in an overfilled condition. I drained some of the fluid out, which still had the dip-stick showing overfull, but I was running out of time to do anything more, and left it as was.

My wife drove the car intermittently over a period of about 3 weeks during which it seemed to run fine to her, but over drive would no longer engage after 1 to 2 weeks.

I just redrained the system and added 3 quarts, and it still shows over full. What is the correct procedure and quantity for refilling the transmission? I find it hard to believe that it takes less than 3 quarts.