First Axle OC UOA Results

[CarbonSteel]

I just received the UOA results from the front and rear axle of my Rubicon (M210 Front and M220 Rear). The viscosity of the oil indicates the factory fill was 80W-90 in both. I would have expected the rear to have 75W-140 in it since I have the towing package and Jeep recommends that oil for towing.

I have to say the UOA for the rear axle is the worst I have ever seen with regards to PPM of iron for such low mileage. For only 5,000 miles, I would not have expected to see 604PPM of iron. To put it into context, the cumulative iron for 150,000 miles in my 2010 FX4 (which had towed 8-9K pounds for at least 60,000 of those miles in temperatures ranging from -22°F to +117°F in the desert and mountains) was 697PPM of iron.

The oil was fairly acidic with a TAN in the 1.47 to 1.81 range, but without a VOA of the oil to use as a comparison, it will not be possible to know if this is abnormal. Most gear oil is somewhat acidic, for example, a VOA of Amsoil 75W-140 I performed found the TAN of the oil to be 3.1

Viscosities for both oils are within specification and nothing else abnormal jumped out at me. I will be keeping an eye on the iron and may perform another UOA in a few thousand miles to ensure the iron is trending downwards as expected. I will certainly not be performing any extended oil changes with the small capacity of these axles. Amsoil 75W-110 was installed in the front axle and Amsoil 75W-140 was installed in the rear.



Enjoy!

Sponsored

 

[MarkY3130]

Interesting stuff. Thanks for sharing it

 

[rockadile]

I assume Blackstone did the UOA? Did they call out the iron as being high or is that strictly from your experience? Have you done any extensive towing or wheeling with your Jeep that would cause the numbers to be higher?

 

[CarbonSteel]

I assume Blackstone did the UOA? Did they call out the iron as being high or is that strictly from your experience? Have you done any extensive towing or wheeling with your Jeep that would cause the numbers to be higher?

No; Polaris did the UOA. I do not use Blackstone because they are too expensive, are not certified, and their reports are anecdotal in nature. I called the iron out as high based upon my experience. I have performed UOAs on dozens of axles (from low mileage to high mileage) and have never seen 600+ PPM of iron in 5K miles. I have not done any towing or wheeling at this point--it has been all straight driving on freeways.


My F-150 and F-250 had UOAs at 13K and 8K and had 429 and 339PPM respectively and there was some towing in those miles. Cumulatively, (which is what happens with iron in oil) it was 697PPM in the F-150 after nearly 160K miles so you can see the reason I raised an eyebrow. I will be pulling another sample at the 10K mile point to see what it is doing and will plan a long-term strategy from there. I hope this is simply a fluke and there is not something happening within the axle, but as most people do not sample oil that early in an axle, I do not have much data to trend.

 

[rockadile]

No; Polaris did the UOA. I do not use Blackstone because they are too expensive, are not certified, and their reports are anecdotal in nature. I called the iron out as high based upon my experience. I have performed UOAs on dozens of axles (from low mileage to high mileage) and have never seen 600+ PPM of iron in 5K miles. I have not done any towing or wheeling at this point--it has been all straight driving on freeways.


My F-150 and F-250 had UOAs at 13K and 8K and had 429 and 339PPM respectively and there was some towing in those miles. Cumulatively, (which is what happens with iron in oil) it was 697PPM in the F-150 after nearly 160K miles so you can see the reason I raised an eyebrow. I will be pulling another sample at the 10K mile point to see what it is doing and will plan a long-term strategy from there. I hope this is simply a fluke and there is not something happening within the axle, but as most people do not sample oil that early in an axle, I do not have much data to trend.

Interesting. I am at 6k and I was gonna wait intil around 15k to do my first gear oil change but I think I am going to do it this weekend since the cost is negligible. I hope you'll update this thread with the next UOA at 10k. BTW, how far out is that looking?

 

[CarbonSteel]

Interesting. I am at 6k and I was gonna wait intil around 15k to do my first gear oil change but I think I am going to do it this weekend since the cost is negligible. I hope you'll update this thread with the next UOA at 10k. BTW, how far out is that looking?

I will update this thread with the 10K results and I am 759 miles away as I type this.

PS...I agree with you changing it now as opposed to waiting.

PPS...this is why I use Polaris - https://x4v5f2p4.stackpathcdn.com/wp-content/uploads/2018/06/2145.02-valid-30JUN20-HOU.pdf

 

[rockadile]

I will update this thread with the 10K results and I am 759 miles away as I type this.

PS...I agree with you changing it now as opposed to waiting.

PPS...this is why I use Polaris - https://x4v5f2p4.stackpathcdn.com/wp-content/uploads/2018/06/2145.02-valid-30JUN20-HOU.pdf

Thanks, after you mentioned Polaris I was reading about them on the BOG site. I can see the appeal of certification but, as a consumer that doesn't have a lot of experience with this stuff, it is nice that Blackstone kinda guides you through the results.

 

[CarbonSteel]

Crossed the 10K mark and took a sample of the rear axle oil to be tested. For only 5K miles on this oil, it is darker than I expected, but then again, I do not have a baseline on this Dana 44 axle so it is hard to tell if this is normal or not. UOA in the mail so I will post the results to this thread when I receive them.

Sample bottle:

 

[wheels082]

I typically do my first differential change at about 5,000 miles. I have not done yet because I am probably going to have it re-geared so I was not concerned with wear on the stock gears. Does this make sense, or are there any other reasons for an early change? I plan to use Amsoil Severe Gear.
https://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-90/?zo=226468

 

[CarbonSteel]

I typically do my first differential change at about 5,000 miles. I have not done yet because I am probably going to have it re-geared so I was not concerned with wear on the stock gears. Does this make sense, or are there any other reasons for an early change? I plan to use Amsoil Severe Gear.
https://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-90/?zo=226468

Since the oiling system is not pressurized and there is no filter you want to get the wear metals out as quickly as possible. If you plan on replacing the bearings when you do the re-gear it's no big deal, but the bearings are the only other consideration.

I used 75W-140 in the rear and 75W-110 in the front. The thinnest viscosity I use is 75W-110 because it is the upper range of the viscosity that 75W-90 used to be before the SAE J306 tables were updated some time ago.

Hope this helps!

 

[wheels082]

Since the oiling system is not pressurized and there is no filter you want to get the wear metals out as quickly as possible. If you plan on replacing the bearings when you do the re-gear it's no big deal, but the bearings are the only other consideration.

I used 75W-140 in the rear and 75W-110 in the front. The thinnest viscosity I use is 75W-110 because it is the upper range of the viscosity that 75W-90 used to be before the SAE J306 tables were updated some time ago.

Hope this helps!

Thanks for the reply!

 

[CarbonSteel]

As promised, 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.

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!

@rockadile - here you go mate!

@DanW - here are the first two UOAs at 5K and 10K (the 10K UOA only has 5K on the oil since I dumped the FF at 5K).

 

[rockadile]

@CarbonSteel Thanks, man...I am just following your lead at this point, .

 

[Brian0128]

Thanks for posting up the 10K UOA.

 

[CarbonSteel]

Thanks for posting up the 10K UOA.

In about 3K miles, I will take another sample and will post it too (it will be 15K on the axle and 10K on the oil).

Sponsored