Should You Change Your Rear Diff at 5k mi if you tow

[UncleJimmy]

EDIT: Summary:

Rear Differential:

I decided to put the data from @CarbonSteel including the temp-mileage interval recommendation, into a table below for reference:

Speed:	Rear Diff Temp:	Change Interval:
65 mph (inferred)	190F	60k mi
70 mph	200F	50k mi
75 mph	210F	35k mi
80-85 mph	225F	20k mi
mountains	245F	10k mi
towing (inferred)	260F	5k mi

*Data is based on Rubicon, 33" tires, unloaded, 4.10 gears.
** If higher load (tires, gears, weight, wind, mountains, extreme heat etc), increase interval.
*** Reduce speed to reduce temps, particularly at the extreme of towing, in the mountains, with large tires, heavily loaded.

Link to original post with data:
https://www.jlwranglerforums.com/fo...-temperature-gauges.41835/page-2#post-1267004

Link or original change interval recommendations:
https://eastcoastgearsupply.com/ft-2536-ecgs-gear-oil-recommendation.html

Front Differential:

Conclusion for the front diff is that it is not too much of a concern with the FAD since it's disconnected when not in 4-wheel drive. Off road, reported temps do rise but not above 200F. See comment below.

Minimal temperatures on the road with the front axle because the FAD prevents the gears from seeing a load. On the trails, the highest that I recall seeing was about 190F, the same for the rear on the trail.

You are starting and stopping a lot on the trail as opposed to constant operation of the rear axle on the road.

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Note: I decided to create a new thread rather than clutter the dana 44 problems thread. If you have not read that and you are interested in your dana 44 then you might want to read that first:

https://www.jlwranglerforums.com/fo...i-think-it-has-been-unreliable-for-me.118652/

I have not seen any information or opinions on the AFE cover. Regarding the nodular iron covers, I doubt they have much influence on the fluid temp. Probably your first step should be to instrument your axle, then make decisions that make sense from that information.

I agree instrumenting the axle is probably a good idea and I may do so. I found some info from @CarbonSteel from 2020 and based on his tests, I can assume I will be in at least a marginal area while towing.

He lists a chart of recommended OCIs that were very interesting based on temps and was even more frequent than I would have anticipated. In other threads, he had reported temps of 245 degrees in the mountains unloaded, which according to the chart would be an OCI of every 10k mi. However, since that is unloaded, while towing it could get above 250 or 260 depending on exact load, grade, wind, time and speed, which would mean a recommended interval of 5k mi or less.

I would say a good rule of thumb for anyone towing (or under other heavy load conditions) would be to increase the viscosity and to change the rear diff fluid at least once per year before your main towing season or 5000k mi, whichever is earlier.

Temp Reference Chart – oil change frequency
o 170 Deg - 100,000 Miles
o 200 Deg - 50,000 Miles
o 220 Deg - 25,000 Miles
o 240 Deg - 12,000 Miles
o 260 Deg - 5,000 Miles
o 260-300 Deg – 500-1000 Miles until Temp is controlled

https://www.jlwranglerforums.com/fo...-temperature-gauges.41835/page-2#post-1267004

In addition, I am still running the stock diff cover. The only one that seems to substantially increase the oil capacity (by about half a quart) is the aFe which is aluminum finned and not particularly durable. If anyone has info on oil capacity of other diff covers, please list them here. I am particularly interested in the Dana Spicer 44 nodular iron cover as I like the fin design for primarily protecting the bolts and facilitating sliding over obstacles (and perhaps some modest extra cooling). I am also considering the DS diff cover for the front and the aFe for the rear but with a slider underneath.

vs.

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[Heimkehr]

Dana themselves recommend 75W-140 for the stock axles on my JLU, in contravention of at least the recommendation printed in the Owner's Manual for the front axle. I therefore use what the axle manufacturer states, and not an FCA copy writer.

As for the frequency of gear oil changes, and without my maintenance spreadsheet in front of me at the moment, I do know that I'll want fresh fluid in each differential no later than Spring of the year when I've any towing planned. While the workload is light -- my loaded motorcycle trailer isn't heavier than 1,400 lbs. -- peace of mind matters.

The stock front axle requires just less than a quart of GL-5 oil; the rear, just more than a quart of the same. Both have the factory differential covers in situ.

 

[UncleJimmy]

I agree, peace of mind, just to have as much margin as possible since FCA/Stellantis seems to have cut out all the margin in all the fluids over the years.

 

[Aonarch]

Are you asking about 5k intervals? No, that is too short.

Or at you at 5k miles and want to swap fluid? I always do full break in fluid change at 1k on all of my vehicles. The Dana 44s are nasty from the factory even at 1,000 miles.

I agree with running 140 weight in the rear, especially if towing. That is what Dana specifies. Jeep chases CAFE standard fuel economy numbers, hence the 90 weight.

20k fluid change intervals would be short, but not crazy.

40k is normal IMO.

 

[UncleJimmy]

Are you asking about 5k intervals?

I'm thinking out loud, more or less.

Based on the only hard data I've seen for these rear axles which I quoted in my thread, a really low interval may be appropriate depending on load, such as towing etc. If you look at the data in those two threads I quoted you'll see the high temps and the failures associated with it.

I think the increased viscosity and oil change interval will help but I am not sure if that is sufficient to protect the electronics in the locker position sensor and the electronic locker engagement mechanism itself, where high temperatures and corrosive, oxidized oil break down the plastic and seals and short the circuit boards. That's why I'm asking for capacities of diff covers.

If the electronics to the locker engagement mechanism fails then that means a whole new D 44 axle and big bucks, so a 5k mi interval may help for those who tow are under heavy loads and reaching axle temps of 250-260F which seems likely based on the data. I'm just not sure it's enough without increasing the capacity and cooling with something like the aFe which I am considering.

 

[Aonarch]

I'm thinking out loud, more or less.

Based on the only hard data I've seen for these rear axles which I quoted in my thread, a really low interval may be appropriate depending on load, such as towing etc. If you look at the data in those two threads I quoted you'll see the high temps and the failures associated with it.

I think the increased viscosity and oil change interval will help but I am not sure if that is sufficient to protect the electronics in the locker position sensor and the electronic locker engagement mechanism itself, where high temperatures and corrosive, oxidized oil break down the plastic and seals and short the circuit boards. That's why I'm asking for capacities of diff covers.

If the electronics to the locker engagement mechanism fails then that means a whole new D 44 axle and big bucks, so a 5k mi interval may help for those who tow are under heavy loads and reaching axle temps of 250-260F which seems likely based on the data. I'm just not sure it's enough without increasing the capacity and cooling with something like the aFe which I am considering.

Be careful with aftermarket diff covers, ESPECIALLY the flat ones:

 

[grimmjeeper]

Be careful with aftermarket diff covers, ESPECIALLY the flat ones:

Good marketing video to sell his diff covers. But he leaves out any mention of any tests that prove the bearings aren't actually getting enough oil. Carrying more oil up and over is fine but a lot of that exta oil just splashes around inside the diff. Once you get enough to flow up and over, more doesn't buy you anything.

 

[Apples491]

I'm running the Dana Spicer covers front and rear. I tow a pretty light (2000lbs loaded) trailer and it only makes up ~10% of my annual mileage. When I swapped the covers on at 10k miles the rear oil was way darker than I liked. I switched to 75w-140 and I'm planning to stick to a 10-15k interval.

In the end, just like motor oil, more frequent oil changes don't hurt. They just increase the time and money you're sinking into it and probably not getting real benefit from.

 

[azjl#3]

while i think the banks would cool better, the fluid dynamics talk is misleading. What fluid are they using that is clear? What is it's viscosity? Why don't they show what their cover does? They could have cut hols like the flat cover, but didn't.

 

[jadmt]

Who here has actually called dana spicer and ask? They told me 75-85 on my rubicon, I did put 75-140 this last change but the 75-85 i removed looked new both times i changed it. next time will most likely go back to 75-85 because I have 3 qts of mopar 75-85 still.. just returned from Moab and traveled pretty fast back and forth and noticed 0 difference on mpg so there is that...I have made this trip 4X's now in this rig...

 

[Terrymo]

My Jeep is used around town and off road. I do 75-140 gear oil change every 3k miles along with engine oil, all filters, and 5 tire rotation. It’s certainly not hurting anything. Maybe wasteful, but still cheaper than hookers and blow.

 

[3TV]

I'm reading this and seeing people changing diff fluid every 3k miles. And I think of Hot Shot drivers that tow heavy with a diesel pickup truck for 100,000 miles without gear oil changes. How many old pickup trucks are there sitting around with 100,000 to 200,000+ miles on them that have never had a gear oil change, and they are working fine.

 

[UncleJimmy]

My Jeep is used around town and off road. I do 75-140 gear oil change every 3k miles along with engine oil, all filters, and 5 tire rotation. It’s certainly not hurting anything. Maybe wasteful, but still cheaper than hookers and blow.

Changing filters too frequently su

I'm reading this and seeing people changing diff fluid every 3k miles. And I think of Hot Shot drivers that tow heavy with a diesel pickup truck for 100,000 miles without gear oil changes. How many old pickup trucks are there sitting around with 100,000 to 200,000+ miles on them that have never had a gear oil change, and they are working fine.

I know, I know, different axles for different applications. And the Dana 44 in a Jeep isn't nearly as robust as the ginormous rear axle in a 1-ton dually truck. I wonder what the rear axle temp is in my 2025 Ram 3500 dually. When I have the camper on the truck and the Jeep in tow on a trailer, I am 540 lbs over the GCVWR at 22,160 lbs. But I am under all axle weight capacities and cargo capacity for the truck and trailer. The truck moves this weight around pretty effortlessly by the way. It has yet to find a mountain grade where it does not have the power to maintain the speed limit.
View attachment 1035058

Nice rig!

The main problem with the Dana 44 for Rubicon are the electronics and the fact that FCA reduced the gear oil capacity significantly. They are not as robust to begin with, run hot and if you fry the lockers it means a whole new rear axle.

I agree, not too good to change filters too often unless you are in dusty environments.

 

[Terrymo]

Changing filters too frequently su


Nice rig!

The main problem with the Dana 44 for Rubicon are the electronics and the fact that FCA reduced the gear oil capacity significantly. They are not as robust to begin with, run hot and if you fry the lockers it means a whole new rear axle.

I agree, not too good to change filters too often unless you are in dusty environments.

I am in a dusty environment. What’s the downside to frequently changed filters?

 

[3TV]

Changing filters too frequently su


Nice rig!

The main problem with the Dana 44 for Rubicon are the electronics and the fact that FCA reduced the gear oil capacity significantly. They are not as robust to begin with, run hot and if you fry the lockers it means a whole new rear axle.

I agree, not too good to change filters too often unless you are in dusty environments.

Good to know. I don't tow with my Jeeps, so fingers crossed.

Both of my Jeeps had the diff fluid changed early. The 4-door was changed at 11,000 miles for a diff cover change and the oil already looked bad. The 2-door was changed at just 1,500 miles for a gear ratio change, and that oil was already starting to look abnormal. I used Royal Purple gear oil.

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