Makes no sense? It was AAMs suggestion in severe usage.Sounds very plausible to me.They wanted it to last in a heavy duty,hard usage application.The import maunufactures wanted the same thing in their vehicles and they had 15k service intervals for several decades.

 

I would not let the factory gear oil stay in the diff any longer then 5K as that stuff was nasty looking and ran out like water when I drained mine. I would think Mobil One could hold up for 30-40K but not 100K.

 

Hounddog is right about what is recommended on the fluid weight. Any GL-5 Synthetic 75w90 in our AAM axles is what is needed and recommended. That said, I don't recall hearing about any failures from running heavier weights.

If you look here at this link----> http://dodgeram.info/tsb/2004/03-001-04A.htm

It shows the 75w140 being recommended for the Durango, Dakota, and 1500 model Rams.

I agree with DBLR that you should change that factory fill out as soon as possible. Mine looked like runny gray paint.

I changed my fluid at 15K then at 30K.....but now I change the fluid every 20K and have always used Mobil 1 75w90 with no issues. Even at 20K it is probably overkill....but I do that along with a host of other maintenance items such as trans fluid, ps fluid, 2 micron filter, etc.

..

 

Do our diffs need an additive for the ls?

 

I use the Amsoil 75-90 and have had to service both a couple of months ago because water got into them from a flood south of Lubbock. Was on the highway and it went in thru the vent tubes!! Fixed that by running them up higher!

Everything looked new on the inside (we took the front diff out to do the axle tube seals when the ball joints were replaced) and that is when the water ran out!!

I never use an additive when the Amsoil is in the diffs. After many trucks and over a million miles have never had a front or rear diff issue.

 

I don't know what Dodge put in my rear diff,but@9100 miles it was jet black and nasty. My rear axle weight is 4000# 24/7 w/my Northstar.Well under what a lot of you guys carry daily. I added a Mag-Hytec and went with Amsoil 75-90 Severe Gear.

 

According to Dodge, no, but there have been a couple of theads about roughness going around corners...

Also, I asked Redline if I should use NS (no additive). He basically said that the 11.5 aam does not require limited slip additive, but the additive actually reduces friction and wouldn't hurt anything... so I went with the regular Redline (which has additive in it).

 

If I remember from what I've read in the owner's manual, the 15K change interval is for heavy duty use, off road, water intrustion, etc. It said change was unnecessary if light duty use only. I don't tow any more except for my bike trailer, don't go off road or ford creeks, so I don't change mine any more.

 

I changed my diffs at 15K, installed MagHytek's on both, because of high road temps in my part of the country and towing pretty frequently I went with Amsoil severe gear 75w140.

About 500 miles before 30K, I sent in an oil sample to have some testing feedback and see IF I really needed to change out the Amsoil fluid. The test results came back telling me that my oil was like NEW oil and they recommended not to change out the oil, retest in 10K.

That testing cost me $20 basically, kit + postage. Much cheaper to have a test done than change fluids when all is good and waste good oil and hard earned cash.

CD

 

changed mine at 25,000 and it needed it.. FYI I also drive a company owned 06 F150 work truck with 175,000 on the clock and the dif lube has never been changed. when it goes they will just have it rebuilt...

 

I'd say I use mine somewhere in between normal duty and severe use. I do occasionally tow about 5000lbs, and I off road probably more than most, often climbing steep hills. So I probably fall in between normal and heavy duty use. I changed stock oil out at 15K, and put in Mobil 1 Syn. Unless someone can convince me otherwise based on my useage, I'm going to 45K before I change again.

Now in regards to weight, I remember there was a service bulletin or at least some talk that while 75W90 was initially recommended (this was in 06 after I first bought the truck), it was later revised to 75W140. Is that correct or am I losing it?

 

That TSB referred to the Corporate Chrysler made axle. No mention of 2500/3500 with AAM axle.

 

Has anyone noticed any difference in performance, noise, or fuel mileage by switching to synthetic gear oil? Also... on a 'different differentially rearend related item of inquiry'... Are the factory rear diff covers rusting on everyone else's truck like mine is? I've seen several going down the road that look like they're doing the same thing as mine. 2006 4x4 - 2500 Mega Cab w/ 30k on the clicker. Seems mighty early to have some corrosion setting in.

 

The axles are factory filled with synthetic and that's what is specified.Yes most ALL factory diff covers have rust on them.Been like that for years.In fact decades.