About to change the oil in the diff and wondering what most of you guys run.
Does anyone use good ol automotive grade 80w 90 gear oil?

That's what's in there.... API GL-5 SAE 90

yep
it's just gears
Hypoid 80-90


unless you wanna spend uber bucks on some other synth-o-mesc version....

yep
it's just gears
Hypoid 80-90


unless you wanna spend uber bucks on some other synth-o-mesc version....

I think the synth stuff is probably a bit over rated and I know in some applications it is more prone to leak.

80w-90 it is then.

Does anyone know if marine lower unit gear oil, (which is GL-5, 80W-90) would be alright?

Does anyone know if marine lower unit gear oil, (which is GL-5, 80W-90) would be alright?

Fine.

I use Motul gear oil with molybdenum.

Regards, Russell

I know a guy who once stuffed bananas into his final drive to quiet it so he could sell it. Long time ago.

I know a guy who once stuffed bananas into his final drive to quiet it so he could sell it. Long time ago.

Pet peeve of mine, Strawboss has it right. There is no Diff-erence, the bike has only a single drive wheel  It's a final drive, not a differential 

The last time I did the change, I was curious of the viscosity difference. I made a basic draw down scale on a piece of sheet metal, laid down the same amount of new and used, and used a draw down bar to see how they compared. New compared to old 6K  miles on the used. And there was no difference in the draw down. The only true diff I found was the viscosity weight. The used was 18% heavier by volume weight. Just a boring day the day I did this, not that it will help.
Ride safe all.
Greg

Made time to change Kawazilla's final drive oil.  Looked like another thing the previous owner had been billed for that was not actually done.  It was obviously in bad need of changing and level was slightly low.
Fresh 80 w 90 in there now and I think it may go down the road a little quieter ...... or maybe I'm just believing that.