This weekend Im going to change my diff fluids. Whats the best to refill with and how much.
I do have one of my rears that loves to spin alot more than the other. Is there a fluid I can run or add to help tighten things up a little?

Thanks Guys, mooseman

 

I put Royal Purple 85W-140 in; no problems with the limited slip in 40K miles.
It is best to jack up each side to remove as much old oil as possible. I THINK it took a little over 3qts--i filled till it started coming out of the fill hole. Check your maunal for exact fluid capacity.

 

Read here:

https://www.dieseltruckresource.com/...ad.php?t=96220

 

i used red line, no problems

 

The Dodge dealer in town told me that I could run ATF +4 in my rear diff. i thought this was odd. is this okay or are they off their rocker?

 

I don't think I would run ATF in a differential. Too thin IMO.

I am running Amsoil Long Life 80W90.

They also have the Severe Gear 75w90

You can get a preferred customer account for $20 a year, and gives you dealer cost on all Amsoil stuff. Its a good deal.

I'm running Amsoil 15w40, 80w90 in the diffs, MTF in the tranny and their ATF in the transfer case.

Its good stuff!

 

Check your manual. They recommend 75w140 synthetic for heavy towing.

ATF??? That is just plain crazy. Why not try running coffee in your diffs?

 

Do you tow often? Do you live in a cool climate? These are just about all you need to think of. You really only have two choices in gear weight, but quite a bit of choices in brands to buy. What sticks out to me the most in your question is that one tire spins a lot more than the other. Well I dont know what you mean but if you've been "one legging" a lot then I can assure you that your limited slip unit is probably pretty wasted. It doesnt take much to burn them up. For example, running a different size tire on the rear down the freeway for 10 miles will ruin a limited slip. So amagine what spinning one tire away on the side of the road will do. Jack up the rear end so both tires are off the ground and spin one tire. It should spin the other tire in the same direction. If the other tire spins the other way then its totaly shot or you dont have a LS. If its a LS then the other should follow with just about the same force, almost. This is whats called break away. The more initial break away pressure you have the tighter the LS unit is. But thats not what makes the unit work while driving. Applied torque is what makes it work while driving.

 

While the fluids draining, Ill lift it up and see which wheel spins which way. If the diff is trashed it will have to wait, Ive just spent my allowance on a full dtt.
Now I need to decide which diff fluid to buy. I dont tow alot but when I do its around 8-10000k so Im sure ill buy a synthetic. Still unsure on what weight and brand will be best.

Thanks to all, mooseman

 

when I changed mine I used the recomended 75 90 full synthetic, the recomended amounts I found in athread here but I can't find it, but if you do the amounts were right on, after doing both I had about 1/2 bottle left over.

 

According to the book, mine came with straight 90 weight, so I just run 80w90.

I'm sure it would not matter if you got 75w90 either.

 

years ago i worked for clark equipment,(michigan loaders ,scrapers , rubber tire dozers.) big equipment, all we ever used in the transmissions was ATF.if the diff capacity was larger 10 gal.it would work great

 

I bought 7 quarts of AMSOIL severe gear 75-140 synthetic and have 10oz. left over.
For only 34,700 miles on the truck there was allot of sludge in the rear but the front looked great.
Thanks for your replies, Mooseman

 

royal purple, 75-140 here. I towed heavy and no problem here. If one tire is off road on mine, it wont spin unless the on road tire loses traction. I bought the mopar friction modifier, and didnt need it. Let us know if it is a LS or not.