That Kyosho stuff is good. I remember it from my K car days.
In the past I always used AE green slime for O rings, then the black stealth grease for gears.

As of now I use the XTR stuff. They have 3 different grease, a copper base, a lithium, and not sure on the o ring grease but they all work well.

This is basic preventive maintenance that ensures good and reliable performance. When I do a full big event prep I pull all my out drives and re grease all of them. I am already changing the diff fluids so its just a little more time and worth it. When it comes to the ring and pinion don't over do it.