Have 1999 Subaru with 170,000 miles that was not driven for about 2 years, ATF and never been changed. (I was not the owner at that time).
Trans. changing was very rough, (I wonder why). Changed ATF, some improvement was noticed, but not good enough. Added 10 oz Lubegard, (red), and noticed vast improvement in tranny.
Have 1996 Dodge 2500 pickup with 100,000 miles. Auto. trans. was serviced by Dodge dealer @ 30,000 miles and also by the same dealer at 95,000 miles. The trans. was shifting rough after the service, so I checked fluid level, dumb dealer overfilled by 1.5 qts. I removed the excess and added 20 oz. Lubegard, (red). After driving about 30 miles, the tranny is improving and I think it will get better with time.
I dont think much of auto additives, however, Lubegard is the exception.