I had a 5 speed manual, that was becoming difficult shifting, hard to get into some gears. Vehicle had 150,000 miles, when I drained the tranny oil, it was actually pretty clean I was surprised., but this was just standard GM 80/90 tranny fluid.
I installed Motul Gear oil ester based, and right off the bat did not really feel a differnce. after 10 miles or so, it got better all the way to about 100 miles, so evidently the oil does somehow impregnate the metal.
Its turned out to be an excellent move installing that, tranny shifts much more normal and smooth