Here is the deal......I have had a couple of sealed gallons of Redline 75-90 sitting on the shelf for probably 20 years. I had gotton it in for a limited slip diff. back then, but never used it, and since my Ram has a limited slip rear, I am thinking it would be a good place to finally use this stuff. Now, what do I put up front? There are several Redline products, some of which I have in stock. I am also hearing Mobil 1 is excellent stuff. .
Also, I am confused as to when this should be changed. It seems to me that the manual reads something like: Change it at 15K if you load it heavy, but if not, don't bother.
Also, is the factory stuff syn. or not?
Could really use some help here.
Thanks in advance.

 

Wow, that oil is older then I'am.

I used Redline 75-90 Synthetic for the rear and front diff's. So far so good. I don't have any qualms with it. 15k is what the manual says change it at, so I would stick with that, towing or not.

I beleive the factory oil is Synthetic, but don't hold me to the wall on that one.

 

I would just recycle that oil. Sealed or not, 20 year oil is too old. Just get some new oil. Oil has changed a lot in that time. Mobil 1 is ok in the diffs, just search and you should find plenty of information.

 

I have mobil 1 in mine with no problems.

 

I decided to call Redline and ask the tech man (Dave). Good guy, company, and product! Dave told me it would be fine to run it, and that it had barely changed in that time. I hear what is being said about its age, and I have til Wednesday morn. to decide. I checked with the man who will be doing the change, and he assured me the ONLY way to go was to pull the plates and clean out the pumpkin. He also reinforced what I have heard on this great forum several times, that I will really be surprised with the difference of the billet TC and VB upgrade........Can't wait!