Originally Posted by Governor
So is the friction modifier in there or not needed at all? My 2011 manual only uses the term once - Mopar Synthetic Gear and Axle Lubricant or equivalent with friction modifier additive. This is describing the 3.6 (which was not even available in ELSD). The 5.7 calls for the Mopar oil without a reference to the additive, so I'm assuming you are absolutely correct unless I see something different. This is new info for me, I had never heard this before. Thanks for the hook up.
No, Mopar 05136035AA does not have fm in it. It is the proper (Mopar) diff fluid for both your 2011 diffs since your rear is non-elsd and while it would not hurt a non-elsd it would be a serious waste of money. The elsd was only standard on the Overland+ I believe so that is why 5.7 is not a clear line in the sand for elsd rear diff.
a little more on previous discussion to clarify a few things...
wk2jeeps is an awesome resource and definitely a virtual bible...it is no more wrong or misleading than the owners manual, just as you are very correct to question me or anything you read on the internet
one should use all resources available to arrive at an actual decision/action as it relates to your vehicle. I personally ref my manual first then go to wk2jeeps for the details/descriptions to include part numbers and really good info all around. We would all be lost without the wk2jeeps resource. The wk2jeeps caution on using the gear oil with fm is more aligned with it's anchoring on the manual (which it should) recommendation of using Mopar fluid which the front diff fluid 05136035AA does not have the fm and since it is not as "exotic" as I call it will likely create chatter if used in the rear elsd. I am pretty sure folks who are stuck on mopar only will buy the mopar fm separate so they can buy the 05136035AA fluid for both since it's cheaper and the qtys each diff require bone you on the amount you buy of the other one with the fm in it. So they just add the separate mopar fm to the rear diff when they put in 05136035AA (normally front diff only)...hope I did not talk in circles there
I am not advocating Amsoil, just happens to be what I use, nor anti-Mopar nor not doing what the manual "recommends" as one is certainly totally safe strictly following the owners manual. There are always areas of "controversy" or less-defined details. The true need for friction modifiers in an elsd is one of them. Gear oils are as different as the range of elsd's they lube. Amsoil even states it cannot guarantee no chatter that's why they offer the anti-slip additive just in case. I am just an Amsoil fanboy because it is so over-engineered and tested I really value the huge margin of safety their snake oils
provide. Many, many other fine snake oils out there. Royal Purple, etc...Pretty hard to go wrong with anything so long as it is the proper spec (API GL-5 in the case of the diff gear oil) and it is properly inspected/changed...I don't trust things that I can't see so I also test all oil that comes out and then do trending samples...just an oil geek I guess.