I'm going to change the rear diff, tranfer case,and front diff oil
Is 75-90 a good oil to go with
Also when I remove the diff covers I'm just going to put silcone on the covers and bolt them back up is that good I don't want any leaks
Thanks
Mike

 

75W90 is great for the diffs. If you do lots severe towing, the owners manual suggests 75W140. If you have an LSD unit in the rear, make sure you get one with a friction modifier in it. I've never had a leak using RTV on the covers, just make a full circle around all the bolts. I also let it set on the cover for about 10 min before screwing it to the axle and then let the cover sit for about 2 hrs before filling it with fluid.

I suggest ATF+4 for the transfer case as there's a seal between it and the tranny. If that seal ever breaks, you don't want those 2 fluids mixing.

 

+1 to squirrels.
here's a little how-to. http://www.pavementsucks.com/tech/diff.php
tip - don't get the old diff oil on your clothes or track it in the house. its stinks bad and wifey will kill you.
tip - when cover if off and drained, spray out the bottom of the case and magnet with brake cleaner to get the sludge out. wipe out all excess and let it dry.
tip - if you have LSD don't be shocked to find broken pieces in the bottom.
tip - don't over tighten the diff cover bolts. they're pretty small.

 

Thanks for the answers
Mike

 

Don't use silicone, use RVT.

 

My owners manual suggests 80w90 for the rear axle and 75w140 for the front.

But others have used 75w90 for both with no ill effects, I believe.

 

i used valvoline 85w90 for both. black rtv for sealant. no problem.