I need to change the final drive oil in my Honda GL1800 Gold Wing, I have some Mobil1 75W-90 gear oil here and it has a limited slip differential additive. Is there any reason why I could not use this in the final drive?
The only thing I'm aware of that Honda calls out for the final drive oil is that it meet GL-5 specs and be in the 80W-90 range.
According to the Mobil website, the "Mobil 1 Synthetic Gear Lubricant LS 75W-90" meets "API Gl-5/MT-1." In short, it ought to work just fine.
Mobil website here.
If I'm not mistaken, GL-5 implies "extreme pressure" (EP) and that's really what's important. Synthetic or not I'm not so sure is all that critical. I've got 20K on my Goldwing using Valvoline Duralube I picked up at the local Checkers. I typically go about 10K on each final drive change.
Good luck on your 5K trip ... safe riding!
What exactly is a "limited slip differential?" And what additive would be provide to address it?
Unlike the shared engine/transmission sump, which bathes the clutch as well ... back in the final drive there's no concern about friction modifiers. In fact, I would think with the hypoid gears you'd want as little friction as possible ... provided the gear oil can stand up to the pressure exerted between the gear teeth.