1992 Yamaha big bear 350 service

[Jimjam]

Hello all,

I'm about to service my big bear and have a few questions,

1. Transfer case oil- I believe this is the same as the engine 10w40? How much do I need for the transfer and the engine?

2. Is there a link for the oil in the transfer case to back and forth between the transfer and engine?

3. diff oil- I'm looking at doing both best viscosity and how much will I Need?

Thank you

Edited November 26, 2021 by Jimjam

[Jimjam]

So I tried to drain the rear diff but the drain plug is stuck, is there another way to get the diff oil out?

[MarkinAR]

Not without pulling it out and splitting the case.  I've had one once that actually twisted the head off the drain bolt.  Sometimes they have never been apart and the iron plug is welded to the cast aluminum housing due to lack of maintenance.

To answer your questions:

1 and 2: middle drive gear is fed by the engine oil.

3: I usually just go with whatever 90W ish hypoid is cheapest.  These don't make a ton of power or go fast so there's not much heat generated.

Edited December 10, 2021 by MarkinAR

[Jimjam]

Cool thank you