You'll get a bunch of opinions on this Shannon. For the most part you want a thin oil on the shaft and shaft bearings/bushings like 3 in 1. Then a plastic safe white lithium grease for the fast moving gears and gear oil on the slow moving gears. Never too much or it acts as a magnet for dirt and debris. For the most part I before I install a gearbox I wd40 it out, run it in an oil bath, clean it up and apply lithium grease on the faster moving gears as oil won't stay. You really just want the gears to look "wet" not gooped with lubricant.