Getting ready to change the gear oil in the diff. Previous owner's records shows that it was last changed about 53K miles ago.

I bought a few bottles of Wally world Super Tech 75W-90 Syn-Blend Gear Oil. I'm now thinking two bottles may not be enough. We'll see.

I guess I have non-LSD so I'm using straight gear oil. If I'm wrong let me know. I'm going to use a Felpro gasket from Advance, vs RTV. It's being delivered overnight as they didn't have it in stock. If worse comes to worse, should regular permatex black RTV work, or do I need specific type, hi temp, etc?

Diff pumpkin has 12 bolts. (2WD)

Glove box says...

DHA Torque convertor lock
DMD Axle ratio 3.55
DRB Axle rear corporate 9

 

12 bolts is the 9 1/4" rear.

It should take about 5 pints of gear oil. Double check on the 75w-90. Dodge recommended the 75w-140 over 75w-90 in some models.

You don't need high temp RTV. They do make a heavy duty oil resistant version.

 

2 bottles will be fine if you're adding the LSD additive too, otherwise you'll be just short. Fluid capacity list that I have bookmarked:

https://dodgeforum.com/forum/2nd-gen...apacities.html

 

I won't be adding the additive. Non LS. Guess I'll have to pick up another bottle.

 

Well, I picked up another quart bottle of Mobile 1 full syn. I put that in along with a bottle of the Super Tech. Looks like 2 was all I needed as I read somewhere that the level should be about 5/8" below the hole. However, the FSM tells me 2.3 quart capacity. Well, I put a little under 1/3 quart and it ran out of the hole. After adding, I saw that the Mobil 1 had friction modifier, which I didn't need. Oh well, it's done already. Hope the fact that I'm a little overfilled is of no consequence.

 

What's a thread without pics?

Fluid coming out looked pretty clean, it was changed in 2011.





Right after I pulled off the cover. The writing on the gear leads me to wonder if this diff was rebuilt. I sure hope it was, since I'm at at 253K. The gunk you see is when I pawed at the magnet.



Another view of the dirty magnet.


Sprayed almost a whole can of brake cleaner and let it drain overnight with the front of truck raised. Looks a lot cleaner...



Shoulda took some pics of the Felpro gasket. As per Felpro directions, I added a light coat of black gasket sealer to the mating surfaces. That held the gasket in place real nice too. So what do you think? Is that writing from the factory, or a rebuild?

 

Mine has writing on it and it has never been rebuilt

Your fluid looks good. Remember, lots of vehicles don't call for differential fluid changes - when you don't have an LSD. The damn clutches make a mess of the fluid fast.

 

Woah that oil looks clean for 3 years old! And yeah the clutches in an LSD must really do a number... the oil in my front dif looked so black after only 15,000 kms (seal was leaking).

 

At least you did not find a small piece of metal broke off from the outer edge of the internal part behind all the cltuches.. lol..

And eww at using super junk.. used some super tec junk before and it was junk junk junk.. almost like that yellow bottles of oil you find at the 'kwick marts'

 

I'm also doing mine, already have some full synthetic 75W-90 fluid, and a tube of friction modifier. Anybody know much friction modifier I'm supposed to add to my differential?

1999 Sport Model
3.9L engine
2WD LSD
5 speed manual