Hi guys. I am up here in Canada where we get real winter, and I have a 2001 3500 4x4 dually. The truck is originally from South Carolina. During the winter, usually at temps of minus 20c or colder, if I engage the front diff for a short time, I have a lot of trouble to disingage it unless I run it for some time to get it warmed up. I'm guessing the gear lube is too heavy. Since I should change it anyway, what grade should I use, and can I leave it in for the summer? Is synthetic an option?

 

80w90 synthetic is best but you probably dont need synthetic in the front diff. I would use synthetic lube in the rear for sure (er, rear differential that is )

you probably have 140 wt or something in there...

 

I use all synthetics. 75w90 in the front. And 75w140 rear. All year, every year.

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I use amsoil severe gear. We got down to -35f here and -48 in ND. I believe sg has a pour point of -60. Welcome to DTR!!!

 

otis.2010

Just try backing up before you try to get it out of 4x4. works for me.

 

You can use synthetic up front if its cold enough during your "winter" to turn the lube gelatinous. You're not talking that much more money and it will only improve action. Oh and..........we also have winters here. What you experience up there is more tortuous than enjoyable.

 

Hey, Thanks for the quick response guys. I'll check this out. I think I'll change oil in the rear as well while I'm at it. The rear one is a limited slip series 80 I think, and I understand it will need a friction modifier added. What is the correct amount to add, and are there any preferred brands?
By the way, how much oil do these diffs each hold? George

 

amsoil 75w90 in both diffs, atf in the T-case, and MTG in the transmission (nv4500) Works good all year long.

**Disclaimer** I know NOTHING about winter.

 

Haha..... That made me laugh out loud.

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This is the 3500 rear differential: http://dodgeram.org/tech/specs/axle/286RBI_specs.html

This is the front differential: http://dodgeram.org/tech/specs/axle/axlespecs.html

If you use a synthetic lube which is highly suggested in such cold climates then just note that some synthetic lubes will already contain a friction modifier. There would be no need to add more and adding more will only reduce limited slip function and adding more than you need could stop all LS function.

 

X2 for amsoil sever gear 75w90 front 75w140 rear

 

Always use a good synthetic if you can. The lube in the front diff is still doing something even if you're not in 4wd.

For clutch type limited slip units, I never add modifier without first doing a test drive, regardless of the type of lube. If it chatters in tight corners, I add some--and then only enough to reduce the chattering. The guys who just automatically dump in LS additive are basically disabling their limited slip.