front and rear diff oil change

[BHaner]

Well I just turned over 16k on Sunday, and I am going to go through and change the oil in the differentials. I remember reading that it had to be synthetic oil... but don't remember the details. I also remember something about not filling them all the way to the cap. Can someone refresh my memory?



Byron

 

[Rosco]

Do a search and you will be flooded with information.

 

[bulabula]

Book says to use Syn 75W-90, fill to the hole (after doing all the math).

 

[GBrzezinski]

American Axles Trac-Rite difs (2003 & newer) do not require friction modifier, & use SAE75W-90 GL-5 synthetic Part# 05102232AA.

 

[Tony T.]

Gear Oil

I just changed mine out a little over a thousand miles ago at 15,200 miles, used Castro Syntec 75w-90 gear oil. It's full synthetic oil, and has the GL-5 rating. Took 7 quarts to do front and back. 3-front & 4-back. Had just a small bit left over when I filled front. Old oil still looked real good.

 

[BHaner]

Ok, I see that Tony T. is using Castro Syntec oil, what is everyone else using? I have used Amsoil series 2000 and Royal Purple before, but they have friction modifier in them. I know it says that it is "not required" but does it hurt anything?

 

[rbattelle]

Friction modifier won't hurt anything, but you don't need it. I used Valvoline Synpower 75w-90. It's full synthetic. I know some have also used Mobil 1 75w-90 (Vaughn Mackenzie comes to mind).

 

[TBrennan]

I'll be using Mobil 1 75W-90 also. Have it in the truck now, just waiting for the right opportunity to get it done.

 

[R.M.THOMPSON]

I had a problem ( I thought) , after a dealer servive at about 15k. Seems as if the dealers original intent was to put in the 140 wheight oil at about $90 an axle and he changed his mind and put in the 90 wheight. Everything still O. K. , until I go to parts dept. to pick up a gallon of atf+4 . Looked at the shelf and found that the part # that was put in my diff's did not indicate that it was synthetic... ..... Sooooo ,I went back over to service and to make a long story short, Had even the service manager and the lead mechanic reserching as to why the parts computer could list this lube as acceptable. After a call to STAR, It appears as if some lube was labelled without the word synthetic on it . The part # from the mopar book explains it all. A word to all is to have parts dept. show you the catalog narrative or at least a copy of the M. S. D. S. sheet on the product before you buy!!!!. BTW ,Casey and others were a great help on this problem.

Mark T.

 

[Rosco]

Originally posted by BHaner

Ok, I see that Tony T. is using Castro Syntec oil, what is everyone else using? I have used Amsoil series 2000 and Royal Purple before, but they have friction modifier in them. I know it says that it is "not required" but does it hurt anything?

I am using Amsoil Series 2000 75w90.

 

[Kamenick]

I stayed with the synthetic, think that's what's most important, but switched from the stock 75w90 to mobil 80w140 to handle the heat of towing and summer temps.