I'm wanting to change my rear axle fluid so I went to the Dodge dealer with my VIN so they give me exactly what I need...yeah right. I looked at my service manual and there are 7 different rear axle #'s and 2 don't require friction modifier (I have a limited slip 3.55). Ok I thought, the VIN will eliminate any confusion. So I give him my VIN and he says it holds 6.8pts and 1 bottle of modifer. He gives me 2 qts of oil and the modifer and dumb me just says OK thanks. On the way home my brain started working...well crap and to top it off, when I got home and checked my service manual the one that holds 6.8pts is a 2wd.Anyway, I've just decided to buy some regular GL-5 to mix with what I have and not go back to the dealer. Back to the original question...how do I know exactly which rear end I have because some call for modifier and some don't.

 

If your truck is a single wheel auto you need the additive,it will be a Dana 70

 

Thats what I was thinking but I changed it @ 20K ago and put modifier (Oriellys) in it and its already messing up. When I turn slow, hard and sharp I can feel it "slipping". Hopefully I put the wrong modifier or something in it to make it crap out so soon. Thats the reason I went to the dealer so I would be sure to get the right stuff. Oh yeah, they wanted $53 for 2 qts of Mopar 80/90 GL-5 and a small bottle of modifier. After I had my fit, they lowered it to $31...still too much but for the piece of mind I guess its worth it.

BTW, can you put too much modifier in it? Or should I just dump the whole little container in?

 

Start with one bottle, drive a few days, if it still chatters add another half bottle. The additive makes the clutches more slippery, so if you add too much it will make your limited slip less effective.

 

What are the symptoms of being less effective? Could I have put in too much the first time and thats whats causing my "slipping" feeling?

 

I would get some 75w90 and 2 bottles of the modifier and be done with it. You should be able to get a gallon of it from oreilly's for less than $30, I wouldnt waste money on the dealers stuff. 2wd and 4wd have the same rear ends, auto 2500 will have d70's and sticks and all 3500 will have d80's.

 

Check out synthetic lube. Check the bottles and you will find that they DO NOT require modifier for LSDs. Clean everything out, add the lube, drive in figure 8's on soft surface for a couple of minutes, and then drive on hard pavement to check for chatter, etc....

 

The Mopar lube doesn't say anything about synthetic on it or requiring modifier. Heck, I'm more confused now than when I started. I just thought the easy thing would be to have them look up my VIN and give me exactly what I need and be done with it...but I guess thats wishful thinking.

I think I've read somewhere that some LSD's don't like synthetic and will give you fits if you use it. I just don't want to tear anything up and be out a bunch of $$$.

 

Try the Royal Purple from Orileys. It has the friction modifier in it, and is full synthetic.

 

Yes...Dana 70 on the 01 & 02 automatics.
But got to Parts Dept, with your VIN#, and ask for a "Build Sheet". It's free and lists everything that came on your CTD from the factory. Good to have.

To test if enough additive, do tight figure 8's in a mall parking lot. Any chipping or drag and you need some more.... assuming it's a LSD rearend.

RJ

 

I still have the sticker inside my glove box that tells me, you might too, but I think RowJ is right.

 

Now I'm second guessing everything. I just looked at my cover and it says Dana 080???? There are some other #'s listed on my cover along with some more on the axle but none match anything in my service manual. Am I just making a mountain out of a mole hill or what???

 

Is your truck a dually? If so its an 80 but it doesnt matter on the lube because 70's and 80's use the same stuff. Synthetic wont hurt anything

 

Nope...single wheel with the camper package. Weird huh?

 

Did you buy it used? Maybe it had an 80 transplanted or the camper special's have 80's? If you tow amsoil makes a 75/110 and a 75/140 but as long as you get a 75/? it will be fine.