I just bought this truck in November. It is about time to change the rear differential fluide. Planning on using Amsoil 75-140 as I tow alot. But, I don't know how much to purchase.

I have reviewed the owners manual and window sticker and I cannot find any reference to which rear diff. I have and what is the fluid capacity. I counted the bolts holding the cover and it has 14.

The sticker shows that I have an Anti-Spin differential.

Here is my vin if it helps: 3D7-ML48C97G-734534.

In case the signature does not display:
2007 Dodge Ram 3500 SLT Quad Cab 2X4 DRW
5.9L HO Cummins
6 speed manual

Questions:
1) Which rear diff. do I have?
2) What is the fluid capacity?
3) Do I need to add the friction modifier?
4) Whick Amsoil oil is recommended?

 

You should have the AAM 11.5" rear end. I think it holds 4 quarts.
Others should chime in and confirm or correct me.

 

In my 06 I used just over 4 qts in the rear and about 3 in the front. IIRC no friction modifier is required also I did not use any in mine when I installed the Amsoil 75/90 sever gear oil and I've had no problems.

 

you have the 11.5 AAM
a little over 4qt's
it does not need friction modifier (gear driven LS)
factory fill is 75/90 synthetic although it looks alot thinner when you take it out...but there is a TSB from DC recomending that you use 75/140 (or similar) for heavy duty applications. Amsoil sever gear oil in either weight is a great choise!!!!!

 

Thanks for the quick replys.

Do I have a 3.73 or 4.10 rear diff.?

 

The 6speed G56 is only offered with 3.73's

 

If you can afford it, go with the Mag Hytec covers on reinstall. You won't be disappointed.

 

Use the new diff fluid. It splits between the 75/90 and and 75/140.
It`s now available in 75/110.
You get the added film without the MPG loss.

 

I just heard about the Amsoil 75w110 an will try it my next change. Does it cost any more then the 75w90 sever gear oil?

 

Well, I just completed changing the rear diff. fluid. It was a simple job. The old fluid was dirty, dark gray and seemed very light weight. The magnet was covered with a thick metal (?) paste. I cleaned everything up before assembly. It took exactly 4 quarts. I filled it to 1/4 inch below the fill hole as specified in the owners manual. There was a fill level imbossed on the cover plate that was about 1/2 inch below the fill hole so I overfilled just a little.

I decided to put in Royal Purple 75w140 because it was available at my local auto store. I tow a lot; 9K travel trailer. The truck currently has about 6,000 miles.

For anyone that has not changed their rear differential oil, you better change it soon. The stuff they put in at the factory is worthless.

 

I too just did my rear diff. Some what easy to do but since DC puts cheap paint on the rearend it was peeling off. I had sand the rust off to repaint the cover. I filled mine up to the line that was stamped into the cover. I used the bread tie method I read on here, thanks to whoever posted that gem of an idea.

Hardest part was putting the new oil in, yeah I knw they make pumps but I did not want to buy one for just the occasional use. I used mObil 1 75w140, mainly cause that is what they had, they were out of the 75w90. Not cheap, 15 bucks a quart plus tax!

Hub

 

Got buddies whom did first change at 90k(front to back) with no issues and towed 90% of the time.Factory fill must be ok in my mind.Fliud at 90k didn't look at all bad.

 

Fac fill is synthetic and we need to change it a 6k ........?

 

6k is a little over the top.In HEAVY use 15k is the interval.Of course it dosen't hurt to change it every 1k if you want to or after break in.The ones I saw drained for the FIRST time at 90k didn't look bad.Heck had to talk both those guys in doing it then.

 

I had under 10k on mine and had hauled very little with it an the gear oil looked like crap so I wished I had changed it sooner. I'm surprised someone would go 90K on factory oil all I can say they must not like to take care for there truck to run it that long. Now the front diff oil still had light golden color to it so I could of waited if I had seen the oil before I pulled the cover but feel beter to know I have good gear oil in it. Being I installed Amsoil sever gear oil the next time I change it I hope it looks a lot better then the junk oil I took out that Dodge put in it.