2019 Jeep Rubicon Rear Axle UOA [10,000 Miles]

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9,102
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Houston, TX
Here is the second UOA on the rear axle. The cumulative iron is 900PPM which continues to set a record from my experience performing UOAs on various axles with varying mileage and use cases. The iron did reduce by slightly less than 50% from the first UOA, which is good and is as it should be, though I would have expected it to reduce a bit further--especially since I upped the viscosity from 80W-90 to 75W-140. I have to say that FCA screwed the pooch on the factory fill since they recommend 75W-140 for towing and my Rubicon has a towing package, yet they filled it with 80W-90. no-no Otherwise, all other elements reduced in count. However, there was some shearing that happened as the viscosity reduced from 26.4 for virgin oil to 22.8 and the TAN (acid) levels were slightly higher at 2.43 versus 3.10 for virgin oil--though this is not cause for concern as most gear oils are acidic in nature. I topped the level off after pulling the sample and I will likely take 2 more samples (one at 15K and one at 20K) before calling it good. Depending on what I see in the 15K and 20K samples, I will determine the OCI for the rear axle and settle into that regime. At 1.6QTs capacity, it is not like I am going to break the bank even if I settle into a shorter OCI than I have with previous vehicles. From a cursory point of view (since I have limited data), these axles **appear** to be harder on oil than larger axles such as Sterling 8.8", Sterling 9.75", Sterling 10.5", and Dana 60 axles. In my experience, none of the aforementioned axles have produced the wear metals nor the shearing that I have seen with this Dana 44. Time will tell if that means anything. At any rate, enjoy! [Linked Image from iili.io]
 
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597
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Ontario, Canada
Did they drastically change the Dana 44 on 2019, than the jku? I bought mine 2013, lady driven..,city slicker garage kept....not a blemish on it and got it for a steal, every fluid changed on time except the husband decided to run 15 k over recommended diff change, when I went to change it, drain plug full of shavings and a few nice chunks came out. After research the clutch style lsd they used were already a bit "iffy" and especially if you didn't maintain it and stay on top of it. I said screw it, put in a new truetrac rear diff. Seeing your numbers I can see even the recommended interval they specified is to long for stock differential.
 

CarbonSteel

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Originally Posted by domer10
Did they drastically change the Dana 44 on 2019, than the jku? I bought mine 2013, lady driven..,city slicker garage kept....not a blemish on it and got it for a steal, every fluid changed on time except the husband decided to run 15 k over recommended diff change, when I went to change it, drain plug full of shavings and a few nice chunks came out. After research the clutch style lsd they used were already a bit "iffy" and especially if you didn't maintain it and stay on top of it. I said screw it, put in a new truetrac rear diff. Seeing your numbers I can see even the recommended interval they specified is to long for stock differential.
Starting in 2018 with the JL series, the Dana 44 is a new generation and the one thing they definitely did was reduce the oil capacity (the general assumption is driven by CAFE which is also why there is a front axle disconnect). Speaking for me, I will only run 75W-140 in the rear versus 80W-90 or 75W-90 and depending on the results at 15K and 20K, I will determine the OCI. It is not possible to know (yet) if the reduction of iron was due to the gears being nearly broken in or if due to the 75W-140 viscosity. The axle operates normally with no noises or issues and the wear patterns on the gears are also normal. One thing is certain, I do not see how the OCI can be anywhere near "normal".
 
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597
Location
Ontario, Canada
O
Originally Posted by 2015_PSD
Originally Posted by domer10
Did they drastically change the Dana 44 on 2019, than the jku? I bought mine 2013, lady driven..,city slicker garage kept....not a blemish on it and got it for a steal, every fluid changed on time except the husband decided to run 15 k over recommended diff change, when I went to change it, drain plug full of shavings and a few nice chunks came out. After research the clutch style lsd they used were already a bit "iffy" and especially if you didn't maintain it and stay on top of it. I said screw it, put in a new truetrac rear diff. Seeing your numbers I can see even the recommended interval they specified is to long for stock differential.
Starting in 2018 with the JL series, the Dana 44 is a new generation and the one thing they definitely did was reduce the oil capacity (the general assumption is driven by CAFE which is also why there is a front axle disconnect). Speaking for me, I will only run 75W-140 in the rear versus 80W-90 or 75W-90 and depending on the results at 15K and 20K, I will determine the OCI. It is not possible to know (yet) if the reduction of iron was due to the gears being nearly broken in or if due to the 75W-140 viscosity. The axle operates normally with no noises or issues and the wear patterns on the gears are also normal. One thing is certain, I do not see how the OCI can be anywhere near "normal".
Hopefully it's just break in, and good thing you are the type to monitor it like this, good call, you probably just saved yourself a expensive repair bill right after warranty was up no doubt! Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
 

CarbonSteel

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Originally Posted by domer10
Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
For clarity, both of my axles are not LSD, they are ELD (electronic locking differentials), I have no clutch packs, but I do know what you mean about the LSD axles, plenty of chatter (no pun intended) about them in the Jeep forums.
 
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597
Location
Ontario, Canada
Originally Posted by 2015_PSD
Originally Posted by domer10
Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
For clarity, both of my axles are not LSD, they are ELD (electronic locking differentials), I have no clutch packs, but I do know what you mean about the LSD axles, plenty of chatter (no pun intended) about them in the Jeep forums.
Thanks for clarifying that, I assumed rubi's would def come stock with LSD, or was it optional? Or do they now use the BLD in place of the lsd? Either way, not being a lsd I hope that is just initial break in! Because if not then they way over shot the factory change on true LSD rear ends if yours continues to show wear such as this.
 
Originally Posted by domer10
Originally Posted by 2015_PSD
Originally Posted by domer10
Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
For clarity, both of my axles are not LSD, they are ELD (electronic locking differentials), I have no clutch packs, but I do know what you mean about the LSD axles, plenty of chatter (no pun intended) about them in the Jeep forums.
Thanks for clarifying that, I assumed rubi's would def come stock with LSD, or was it optional? Or do they now use the BLD in place of the lsd? Either way, not being a lsd I hope that is just initial break in! Because if not then they way over shot the factory change on true LSD rear ends if yours continues to show wear such as this.
Rubicon's have lockers, no other differential option is available for a factory delivered rubicon.
 

CarbonSteel

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Originally Posted by domer10
Originally Posted by 2015_PSD
Originally Posted by domer10
Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
For clarity, both of my axles are not LSD, they are ELD (electronic locking differentials), I have no clutch packs, but I do know what you mean about the LSD axles, plenty of chatter (no pun intended) about them in the Jeep forums.
Thanks for clarifying that, I assumed rubi's would def come stock with LSD, or was it optional? Or do they now use the BLD in place of the lsd? Either way, not being a lsd I hope that is just initial break in! Because if not then they way over shot the factory change on true LSD rear ends if yours continues to show wear such as this.
ELD axles are "better" than LSD because they are true lockers meaning there are gears that electronically engage and "lock" each axle into operation versus an LSD that has clutch packs inside and will wear out over time. As far as I know, there was no other axle option for a JL Rubicon (other models had options) and I am glad because I have never much cared for LSD axles. I had ELD on my F-150 and F-250 prior buying the Jeep and I was very happy with the offroad capabilities.
 
Messages
597
Location
Ontario, Canada
Originally Posted by 2015_PSD
Originally Posted by domer10
Originally Posted by 2015_PSD
Originally Posted by domer10
Many in the Jeep community, especially new comers do not think about diff fluid because of previous vehicles being owned and not owning a LSD and just at minimum following the manufacturer recommended change, but this rear end and jeeps in general are a whole another beast.
For clarity, both of my axles are not LSD, they are ELD (electronic locking differentials), I have no clutch packs, but I do know what you mean about the LSD axles, plenty of chatter (no pun intended) about them in the Jeep forums.
Thanks for clarifying that, I assumed rubi's would def come stock with LSD, or was it optional? Or do they now use the BLD in place of the lsd? Either way, not being a lsd I hope that is just initial break in! Because if not then they way over shot the factory change on true LSD rear ends if yours continues to show wear such as this.
ELD axles are "better" than LSD because they are true lockers meaning there are gears that electronically engage and "lock" each axle into operation versus an LSD that has clutch packs inside and will wear out over time. As far as I know, there was no other axle option for a JL Rubicon (other models had options) and I am glad because I have never much cared for LSD axles. I had ELD on my F-150 and F-250 prior buying the Jeep and I was very happy with the offroad capabilities.
Sorry I misread and misunderstood, some reason I thought I saw BLD, meaning brake lock style lsd. Cause I know rubis had a locking diff.
 

CarbonSteel

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Originally Posted by domer10
Sorry I misread and misunderstood, some reason I thought I saw BLD, meaning brake lock style lsd. Cause I know rubis had a locking diff.
No worries! Cheers2
 
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Is it surprising, in your view, that the phosphorous and oxidation values were higher with the FF compared to the Amsoil SG?
 

CarbonSteel

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Originally Posted by claluja
Is it surprising, in your view, that the phosphorous and oxidation values were higher with the FF compared to the Amsoil SG?
Not so much and without a virgin sample of both it would be difficult to know if it is an issue or not.
 
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