Car with no power to Move?

Joe,
I gave up. Sold the 2001 Honda civic to a junk yard. Obviously, a transmission issue, not worth doing anything further.
For other old cars, I plan to work on them like this: drain one quart, add a fresh quart, then drive 2000 miles before repeating the process. I'll do this five or six times to complete the entire process, which I believe will be safe.
Thank you for all your great help.
Ming