Your sure right about those tall gears, I think it must have been the heat. there is a threshold at which the harmonics of hypoid (or ANY) gears tear themselves up, and those low ratios got up into that on the road. Synthetic lubes have helped that issue dramatically. As far as the Jap stuff? I dunno, Honda and Toyota make the best automobiles on the planet, hands down. best engineering, best metallurgy, period. Galls me to say it, they did their best to kill my grandfather and take over our country once, but it's true.
Condensation is a factor, but mostly on short-trip stuff. If you drive more than 30 minutes once a week to boil it off this shouldn't be much of a factor unless you live in Seattle or someplace like it.
BTW, depending upon what kind of transmission that Honda you mentioned had, the engineers may have been interested in checking their final drive stuff. Some Honda FWD manual and auto trannies had separate oil for geartrain and final drive. Often, the final drive oil was neglected (few mechanics knew to check it/change it separately from the main transmission oil) and it tended to leak out gradually at a case seam, causing dry run damage. Also, Honda pioneered the use of high-efficiency "0" weight automatic transmission oil, the stuff pours like milk. MUCHO research and failure analysis had to be done to effectively understand what would be required to make a tranny work with oil that thin.
boy, I can sure hijack a thread, can't I!
Sorry 'bout that!
Gear