Well, with all the discussion here about synthetic oils and with my Diesel tech's advise, I change out both front & rear diff's and replace with synthetic gear oil. Not really believing that there is much difference between brands of oil, my brother-in-law who works at an auto parts supply house and gets me things for cost, got me a case of Valvoline syn gear oil. Replaced the gear oil, both front & back and down the road I go. Well, after a couple of days I'm smelling gear oil. Didn't give it much thought as both times I was following a truck that was burning oil, yet it did smell like burning gear oil. After 1 week, I'm heading up to Montreal and I get out at Canadian Customs to check in and I'm smelling burnt gear oil really bad. I look under my truck for any leaks and notice the paint is gone from rear diff cover!! I went to touch the cover and oooouch!!! It was hot enough to fry eggs!! I stay there long enough for things to cool down and pop the plug to check the level. Yuuccchh!! The oil was like black sludge and stunk!! Well, there's nowhere around to get anything fixed, let alone I only had US cash. So I went to my delivery where there was a Dodge dealership right down the street. They were too busy to get me in until the next day. So, I buy a couple of those bottles of anti-friction additives figuring I could get back home as the rear just started making noise under low speed. Got home OK and went to my dealer. They checked it out and sure enough the rear was burnt and pieces of metal were stuck to the magnetic plug. The oil that was still pretty much liquid was the consistency of water. They determined that the oil must have broke down and decided that the entire rear needed to be rebuilt, from the axle bearings in. As I was about to grab my butt waiting for the price tag of this decision, the tech told me that he was going to put it in as a warranty repair and saved me a coronary!! The lesson here, as explained to me by the Dodge Service Manager & Diesel tech, is to ALWAYS use MOPAR fluids!! What was I to say to that?? Absolutely, YES SIR!!

 

Happy to hear they are going to cover your rear under warranty. I'm not so sure I agree with using MOPAR fluids in everything. I do keep ATF+4 in the tranny but in the differential, I have Mobile 1. It has been in there for a few thousand miles now without a problem. I initially put AMSOIL 75W-90 in there and I drained it out the same day becaused it caused my differential some chattering/clunking sounds.

One thing for sure, if the truck is under warranty, and you're using what is suggested, all will be fine if something goes wrong and the truck needs repair.

 

Thank goodness they are covering that item under warranty! Did you happen to ask what the cost would be just for curiosity?

I thought the fluid from the factory was synthetic too. Is that not right?

What weight oil was the Valvoline that burned up?

It is my understanding the Valvoline 75w90 would have been fine to use. I considered it myself, but in the end I went with the Mobil 1. So far no problems. And I added no friction modifier and was told it doesn't need it.

 

Actually, I was afraid to ask how much if I was paying!! The truck has 64k on it. The dealer charged me $100.00 for the warranty repair as I have the extended warranty coverage. The manual calls for 75/95 weight syn gear oil which is the weight I put in, however the tech in Canada told me that when they replace the diff oil, they use 80/145 syn oil.

Also, after the fact, I just found a TSB re: 3500 Dodge. They placed the check plug too high on the diff cover and if filled, as normal, to bottom edge of check plug hole the diff will be OVER-filled and will cause foam. This is exactly what I did and when I checked the level, after taking it for a test drive, there was alot of foam coming out of the hole. I mentioned this to my brother-in-law as I do not have any experience using syn oils, but he couldn't tell me anything about the foam.

Also, would like to plug the dealer as they have been exceptional in taking care of me with this and some other things even though I didn't purchase the truck there. I guess I can't mention their name, but their located on Business Rt#30 in Downingtown, PA. They are really great folks to deal with!!

 

The first thing I do in my oil burners (all brands for 22 years) is switch to Mobil 1 fluids if they are availaible! I have never had any lube issues trannys, diff's, trans case or engine in that time! I did use the Amzoil replacement fluid (trans-synd) on my Duramax but other than that only Mobil 1 products. Good Luck!

 

That's funny. Not to hijack your thread, but last year, when I had a truck on order from them, I found out that they are the biggest, lying slimeballs around. I cancelled my order, and bought from another dealer.

We now return you to your oil thread............

 

Just for everyone's information and to answer the question asked ealier in this thread. These trucks are filled from the factory with 75w/90 synthetic gear oil. I am not for sure on this part but most of dodges other oils are made by mobile 1.
Just a little FYI.
TRAVIST

 

Hmmm.... I used Valvoline at my 15K change. I'm at about 32K now and haven't had the chance to get to the auto shop to change out the diffs (oil done thru my DC incentive right at 30K). No issues with mine so far and I towed some with it during this interval. Once I get my paper done, I'll be reserving some time at the auto hobby shop and changing out, probably with Mobil 1.

 

it will not be overfilled.

the factory spec for filling the rear end is 1/4" below the fill hole ±1/4"... so 1/2" under the hole to level with the hole is within factory spec.

 

Hope someone at the dealership doesn't decide to send in your gear oil for a sample... they might figure out it isn't stock like gear oil and be bad jujus.

 

I am running Valvoline 85/140 full synthetic in mine for quite a few miles now towing heavy.

 

gmscott good to hear they took care of you. we do use 75/90 synthetic oil it is the exact oil recomended by aam comp. on the front of the bottle it specifies for use in aam axles in dr trucks.
d12