Is 85-140W gear oil too thick for tranny & final drive?

[Gubro30]

I read in Frankenduck' lieberry that moving up to a 75-140 oil would improve smoothness and shifting a bit; I can get ahold of BelRays hypoid gear oil which is 85-140W here.

Is it too thick? I would guess a thicker oil could only help protect the gears right? Since gears and final drive are basically soaked in oil and there are no tiny oil passages like in an engine, it shouldn't cause any problem due to the added thickness?

Thanks!

[mjydrafter]

I added some Amsoil 75w-140 about 2 weeks ago, it did smooth the shifting up.

I really can't imagine the 85-140 not working, if it's all you can get.  Is it a synthetic?

I have Redline heavy shockproof 75w-140 in my final drive, it's supposed to pour like a 140 but have the film strength of a 250.  If I had the proper amount leftover I would have tried it in the tranny.

The only thing I could see happening would be a bit of bit of drag because of the thicker fluid, ie slight power loss or mileage loss.  I have a feeling you might not notice it. :dunno2:

If it gets really cold at your location, but you can still ride you might notice it a bit then as well.

[frankenduck]

Moly additive makes a noticeable difference in the trans.