About 7-8000 miles ago I fixed my 5th gear nut. When I re-filled the transfer case I just assumed that it was like any other one I have worked on and used regular 80w90 gear oil (I know that you should never assume anything). So that is what I filled it with, and the other day realized it took ATF. So should I go ahead and switch it back? Will the gear oil hurt anything? A local mechanic told me it would be fine, but I'd hate to ruin my t-case. Just curious as to what you guys thought.

 

I would think it would be fine.

But with that said, I would switch it to ATF whenever I got a chance if it was my truck. But I don't think you will damadge it with the gear oil.

 

I agree here

ive never seen one that runs with gear oil before, (maybe the 205) but u can just drain it out and put the ATF in it, u might need a suction device, vacuum or pump, but it shouldnt be a big deal..

Rick

 

I have a new process 208 in my old 81 chevy. Who ever had the truck before me put 90w gear oil in it I found out when I checked it. I Re filled with atf. That was about 20 years ago. Never a problem, still works good.

 

From what I hear the ATF gets into the bearings better because its thinner than the 90W oil. I know in my T-5 standard tranny in my 5.0 Mustang gear lube is a no no, ATF only in those just for the reason I stated above.