Thanks Big E & Marc for your advice and replies.
I'm 58 - and this as planned is my last truck - & - wanted to just do things right to help it perform properly to & through retirement.
right now I am leaning towards the Red Line GL-5 75W-90NS & Castrol Longlife 75W-90 Syntrax.
Possibly Mobil Delvac 1 (75W-90) if I can find it on sale.
Locally - Automotive stores - I couldn't come across not one brand of GL-5 Gear oil that didn't contain the LS additive.
figured I would now - go to on-line ordering.
The Eaton rep - we chatted with replied with - the Unit to perform as designed requires (Not Recommends) a GL-5 gear oil that does not contain the LS additives.
The AAM rep - some what beated around the bush - but did reply - the unit will perform fine with a gear oil that contains the LS...
I have read/been told the Eaton design (Anti-Spin) - worm gear/torsion type (Anti-Spin) needs a gear oil that does not contain the LS additive to perform as designed. (This unit is totally different then the Clutch Type).
Was curious if any member has experience with this?
With my 17 Ram - New - I drained the initial OEM gear oil @ 15K mile mark - after towing our 12Klb 5th Wheel for over 6K miles.
The drained gear oil contained a small amount of shiny metal glitter within it. (Magnet showed it was metal)
Replaced OEM cover with much larger PPE w/drain plug (for...