10-29-2018, 10:18 AM
WF Supporting Member
Join Date: Sep 2014
Location: Cheyenne, WY
80W-90 is the norm. Towing 75W140. If you have a clutch type limited Slip Diff (LSD) you will need to have either lube with friction modifier or get the small bottle of additive. Most brands now have modifier in it.
If you are adding TrueTracs, then no modifier should be used. BTW, kinda a PITA to find. IIRC Front is 1.3 and rear is 2.1qts. Buy 4 and you will be golden. There is a drain plug on the bottom of the dif. Then open the fill plug and fill until it comes out.
1) Lube specs are different than motor oil. The "W" stands for winter, in 80w90: 80 is cold and 90 is warm. If you live in extreme cold areas you want the first number low. If you tow or in a high temp (ie AZ) you want the second number to be higher. I tow, live in WY (low but not extreme low winter temps) but I use 75W140 to cover all bases.
2) When adding lube, it is way thicker than motor oil. When the level gets near the top of the fill hole, squeezing the bottle hard will add way more than is needed. Imagine a slow thick wave hitting the shore. Once this "wave" hits the fill port it will drain and drain and drain. The first time I did it, I wasted a good few oz.
3) When regearing you will have a break in period, usually 500miles. Then the fluids will need to be changed again. So I would buy some lower cost lube, then refill with "the good stuff"
4) When the guys did my regear, I also bought lube locker gaskets. This way when I did my own post break-in change, I could take the covers off and do a visual inspection. Just to look for weird stuff.
5) Unless the lube label says either "LSD require additive" or "top-off LSD only" then the lube will have modifier in it already. Putting lube with additive in a open diff (no LSD) will not hurt anything. People like me with TrueTracs have to search for non-modifer or pay $$$ for MOPAR lube.
6) The gear change is not as simple as taking the old out and slapping new in. Clearances, shimming, pressing bearings in etc was more than what I was willing to do. I have heard plenty of DIY'ers do it fine, but there are a few that have had not so much luck. I paid $900 for the ease of having someone that knows the tricks to do it faster and then someone to holler at if some thing went wrong.
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