I'd stay far far away from bottles of magical goo. In my younger days while driving junkers I killed two cars trying to "fix" problems with bottles of magic. One was an engine sealer treatment the other a fuel system treatment. Either case could have been a coincidence but hard to imagine both were.
With old trannies the most aggressive thing I'd do is drain/fill and change filters. Never any flushing or similar. Honestly, if it were shifting properly I probably wouldn't do anything. It's like the old saying and like someone mentioned... if it isn't broken don't fix it.
