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Everyone should change the differential fluids sooner rather than later

Whatscooking

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I would suggest everyone change the differential fluids sooner rather than later. Just opened up the plugs on mine with less that 3000 miles and the rear looked like it needed changed. The front was good but i am changing it also. Sport S with the tow package but not diff lock.
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kelkolb

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Getting ready to do mine at 19k miles. Owners manual says 20k so we'll see how it looks..... Mobil 1 75W-140 going in
 

Mac

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What did it look like? Dark oil doesn’t necessarily mean it needs to be changed.
 

Willys2Gladiator

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Suggestions on gear oil for those with LS diffs?
 

kelkolb

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guarnibl

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Mine was inspected at 20k, was fine. I changed it anyway at 27k.
 

MrZappo

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I would suggest everyone change the differential fluids sooner rather than later. Just opened up the plugs on mine with less that 3000 miles and the rear looked like it needed changed. The front was good but i am changing it also. Sport S with the tow package but not diff lock.
It "looked like" it needed to be changed? At 3000 miles?

Did you send a sample for testing? Visual inspection does not mean much.

If it actually needed to be changed at 3000 miles than you have serious issues in your differential and a fluid change is the least of your worries.

The front looked good but your changing it anyways?

It's your money but I'd bet that none of this was necessary in the least.
 
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Whatscooking

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It "looked like" it needed to be changed? At 3000 miles?

Did you send a sample for testing? Visual inspection does not mean much.

If it actually needed to be changed at 3000 miles than you have serious issues in your differential and a fluid change is the least of your worries.

The front looked good but your changing it anyways?

It's your money but I'd bet that none of this was necessary in the least.

Yep your right but my money my Jeep. I also replaced the engine oil at 950. Did i send off the oil for analysis, no. I cut open the filter and I inspected myself and found significant metal which I know is not unusual . I do not care for that slurry circulating inside my new engine. Didn't need a labs recomeditition to see that.
I have spent a considerable ammount of time on this fourm reading about maintence. There have been several discussions about the rear diff oil being black so i thought i should check. No metal only this black goo that has filled up the drain plug well. It looks like friction materal from a limited slip disc but mine doesnt have LS according to the build sheet.
I made my living for 25 years maintaining a fleet of 40 delivery trucks from one end to the other. I can safely say i have seen more internals of engines and differentials than most people would ever care to see. Do what you want, really i do not care but for the person that wants to get the max life out of their 45,000 dollar investment you better take a look. For the measly cost of a quart of oil i will change my oil as i see needed.
Ow and dont worry i recycle the used stuff. I use it to help heat my shop.
 

DanW

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I just changed the diff fluid, Transfer case ATF+4, and manual transmission Synchromesh fluid in a buddy´s JK. 168,000 miles on the original fluid. YIKES! The diff fluid looked horrible, but was better than I thought it would be. The transmission fluid looked like diarhea.

The ATF+4 in his T-case still had a slight red tint to it, so it probably had the least wear on it of all, but it still was pretty bad.

I think his Jeep wanted to give me a big hug afterward. My JL´s diff fluid looked ready for a change at 25k. I did it again at 39k and things were much better. I´m going to settle in at 25k intervals from here, out. I´ve got Mobil 1 gear lube in there now.

Surprisingly, my friend´s ring/pinion teeth look fine and his transmission shifts just like my JK, which gets changes every 25k. I´d NEVER do what he did, but it appears to have survived. That said, he doesn´t tow and has not done any hard off roading.
 

Ohio JKU

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I checked my differential fluid/s several times before changing in my jku...

In my youth, numerous old farm trucks went decades on old oil / fluids but weren’t daily drivers or as precise... I’m personally skeptical that the interval needs to be so short, but I do check level and clarity & generally follow the maintenance schedule unless is obvious one way or the other. I was taught to shine a light (or sun) through it, dip your finger and rub, looking for particles/shavings and not “cloudy or worse milky”

as noted: towing and off-road use would be a case for more frequent changes. Any water crossingis a good reason to change too...I do/did tow a utility trailer quite often but otherwise the miles are majority work commute / highway (topdown and doors off if over 60 and not raining....)
 

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DanW

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I checked my differential fluid/s several times before changing in my jku...

In my youth, numerous old farm trucks went decades on old oil / fluids but weren’t daily drivers or as precise... I’m personally skeptical that the interval needs to be so short, but I do check level and clarity & generally follow the maintenance schedule unless is obvious one way or the other. I was taught to shine a light (or sun) through it, dip your finger and rub, looking for particles/shavings and not “cloudy or worse milky”

as noted: towing and off-road use would be a case for more frequent changes. Any water crossingis a good reason to change too...I do/did tow a utility trailer quite often but otherwise the miles are majority work commute / highway (topdown and doors off if over 60 and not raining....)
Big yes on water crossings, and I´d change asap even if you don´t see evidence of water. I ruined rings/pinions in my YJ that way. I checked the diffs and they looked fine. Then drove many hours home. Within a week, I felt the vibration as the teeth became pitted. All it took was about a teaspoon of water. It had gotten above the breathers.
 

Mac

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Yep your right but my money my Jeep. I also replaced the engine oil at 950. Did i send off the oil for analysis, no. I cut open the filter and I inspected myself and found significant metal which I know is not unusual . I do not care for that slurry circulating inside my new engine. Didn't need a labs recomeditition to see that.
I have spent a considerable ammount of time on this fourm reading about maintence. There have been several discussions about the rear diff oil being black so i thought i should check. No metal only this black goo that has filled up the drain plug well. It looks like friction materal from a limited slip disc but mine doesnt have LS according to the build sheet.
I made my living for 25 years maintaining a fleet of 40 delivery trucks from one end to the other. I can safely say i have seen more internals of engines and differentials than most people would ever care to see. Do what you want, really i do not care but for the person that wants to get the max life out of their 45,000 dollar investment you better take a look. For the measly cost of a quart of oil i will change my oil as i see needed.
Ow and dont worry i recycle the used stuff. I use it to help heat my shop.
What filter did you cut open? On the 3.6 the oil filter is an element you can just spread the pleats to see if it trapped anything. I do not know about the diesel maybe it has a conventional metal oil filter.
 

Willys2Gladiator

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@Willys2Gladiator

Royal Purple and Valvoline, both have the necessary additive, so no need to add Mopar additive.

IF a vehicle does not need additive it is aok to use a gear oil with the additive.

Go to the link I gave in the last post.. The info in that JL Wrangler forum is correct and the info in regard to fluid and what to use pertains to both the JL and JT. The post also has info in it that will save you lots of $.

.
Thank you!
Appreciate all the info.
 
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Whatscooking

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What filter did you cut open? On the 3.6 the oil filter is an element you can just spread the pleats to see if it trapped anything. I do not know about the diesel maybe it has a conventional metal oil filter.


I cut the paper off of the engine oil filter cartridge so i could spread it out real good, i know it filters outside in but i wanted to get a good look. Gas engine.
I just finished up with my diff oil change and discovered the bottom drain plugs both have magnets in them, i assumed they were hollow like the fill plugs. Rear still had quite a collection of the black stuff. I scraped that off and took a magnet to it and it appears to be finley ground metal, looks like graphite.
 
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AZCooWhip

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Doing the fluid change on the differentials of the JT, is easy easy for most.

Valvoline and Royal Purple both have the necessary additive so no need to add any more additive.... if your vehicle does not need additive then no harm using the fluid with the additive..

You will use 75W90 in both front and rear diffs, unless you have the tow package and if you have that, you use 75W140 in the rear instead of 75W90.


When reading there, you will see the Valvoline FlexFill pouches being mentioned... They are terrific...

Here is a post that explains a lot,.. especially for those that have the tow package and need to run 75W140 in the rear diff.. https://www.jlwranglerforums.com/fo...-change-differential-fluid.41800/post-1366896
Pepe, this is great information to have. If anything, there is a ton of info out and can be somewhat confusing nor newbs. Diff # this, weight # that, to locker this, LSD that, tow this, no tow that. Coming from HPDE, it was gears that made you go faster. Oil out. Oil in.

I do have one clarification question. On a Rubicon with the Dana44 axels and full front and rear lockers, it is not exactly clear what weight to use front and back. No towing to be done. Any suggestions? 90 or 140 for both with Yukon 4:88 gears?

Thanks in advance.
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