The rear diff in my 2000 3/4 ton is having fits on light turns in reverse. When I got the truck, among a bunch of other things, I changed the fluid. I put in Mobile 1 75w140 LS. Its supposed to have the additive already... Then I was having those kinds of issues, so I added a bottle of Mopar additive. No change. Tonight I was talking to someone selling a dana 60... he said he puts in Valvoline 75w-90 and TransX additive from NAPA - like the full bottle (from what I can tell 7 ounces). The Mopar stuff is 4 ounces.

So what should I be putting in this dana60 rear?

Thanks!

 

Either will work. May just need to add more friction modifier.

Were the retainer clips on your rear diff still intact?

 

Didn't see any problems, but that was a while ago (over 2 years). I used the same stuff in my 04, didn't add any modifier to it. I'm trying to decide to either drop it off at the driveline shop, or pick up another d60 ls 4.10 rear. But if either viscosity works, I'll go to walmart and pickup their brand synthetic 75w90 and drop two bottles of mopar additive in it and see what happens.

I've been reluctant to do that, since I can't really fix what I find anyway and that change (with Mobile 1) ain't cheap, and I gotta wait a day for the permatex to setup before refilling (yeah, I'm impatient!). Walmart stuff is very affordable, like $6 a quart for 75w-90. I think the dealer charged me $8 for a 4oz bottle of additive. Or maybe just buy that transx stuff from napa and see what happens.

 

I don't think the brand name on the bottle for the friction modifier matters very much, it's pretty much all the same stuff.

 

Another point of reference, seems like it happens more once its being driven a bit - like the rear gets up to temp then it really starts having a fit. Seems like the 140 part could be a suspect.

 

I would keep the 75w140 in there, especially if you use your truck for towing and hauling. I run 85w140 in all of my axles, and I use the Walmart gear oil.

 

I have a 18 foot 7000lb car trailer that I'm getting inspected very soon. I don't tow 7k often, but its an all steel trailer and weighs a couple thousand on its own supposedly. I gotta get the rear behaving... can't go into winter like this.

 

What problem are you having? Regardless of what it is, putting a thinner gear oil in won't help anything.

 

Its like sticking clutches, but really BAD sticking clutches. I'm assuming its the diff.... no smoking gun yet. I have another bottle of mopar additive... perhaps toss that 4oz bottle in there and see what happens.