Diff fluid - Wrangler JL

[Remorseless]

Thanks for the info. I do a ton off-roading her win colorado. Maybe I should drain mine and replace with the Royal Purple 75w-140 instead of 75w-90 I put in a couple weeks ago.

Personally I'd run it, just a shorter lifespan than a typical fluid change. If you're stressing your gear oil a lot - lots of highway and lots of trail - I'd be on a short change interval anyway. Just shorten that change interval a touch more, change it a bit earlier, and try not to be Mario Andretti on the trails and highway in the meantime.

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[CarbonSteel]

Thanks for the info. Would it best to switch both back to 75-140 or could I leave the front at 75-90?

I would change the rear to 75W-140. My front axle never sees the load or temperature the rear does even when slow rock crawling so you would be fine with 75W-90 upfront.

Move to 75W-110 or 75W-140 in the front when you change it next time.

 

[rockadile]

Because I have some left (prior to this last OC, I was running 85W-140 in both axles) AND my point was not about the front axle, but the rear which is 100% in operation while it is driven. When I run out of 75W-110, I will be using 75W-140 in both.

75W-90 = 16.0 cSt @ 100°C
75W-110 = 20.5 cSt @ 100°C
75W-140 = 25.9 cSt @ 100°C

Ergo:

75W-110 is 22% more viscous than 75W-90
75W-140 is 21% more viscous than 75W-110
But 75W-140 is 38% more viscous than 75W-90

Given that most Dana 44 M220 axles run at about 210°F at 70MPH at 85°F ambient temperature unloaded--which would you rather have in your rear axle?

Kinda the situation I am in, I have another 3qts of Amsoil 75W-110 and am contemplating if I should just use it for both, use it in the front and get 75W-140 for the rear, or don't use it at all. I don't do any hardcore off-roading. Thoughts? What brand are you using/recommending? I figure I'll stand on the shoulders of a giant since you do all of the UOAs. Thanks, man.

 

[jason0341]

I would change the rear to 75W-140. My front axle never sees the load or temperature the rear does even when slow rock crawling so you would be fine with 75W-90 upfront.

Move to 75W-110 or 75W-140 in the front when you change it next time.

Appreciate you answering my questions. Thanks

 

[CarbonSteel]

Kinda the situation I am in, I have another 3qts of Amsoil 75W-110 and am contemplating if I should just use it for both, use it in the front and get 75W-140 for the rear, or don't use it at all. I don't do any hardcore off-roading. Thoughts? What brand are you using/recommending? I figure I'll stand on the shoulders of a giant since you do all of the UOAs. Thanks, man.

I would use the 75W-110 in the front (since you have it) and 75W-140 in the rear.

Amsoil, Mobil, Valvoline, Castrol, Chevron, and Schaeffer's are all outstanding oils.

I had very good service with Amsoil in my 2010 F150 FX4 and 2015 F-250 Power stroke. I towed heavy in the 2010 for 45% of the 160K miles I put on it and the UOAs were stellar.

 

[Old Dogger]

I use Lucas 75W90 front and rear. But if one plans on towing, then 75W140 in rear

 

[Barely Krawlified]

I’ve performed two complete front/rear differential fluid changes on my 2019 JLUR and it sits with a hair under 27K on the clock.
I daily my JLUR about 25 miles round trip each day and try to at least mildly stretch its freeway and off-road legs at least once a month.

I’m running Valvoline Full Synthetic 75w-140 in both the front and rear and have had excellent results with that fluid in my Dana 44s.

Given it’s price point, ready availability, Chrysler MS-8985 certification and for those of you with the limited-slip diffs it also has the friction modifier included, it’s pretty hard to beat.

 

[grimmjeeper]

Does anyone have any evidence of gears/bearings in a JL/JT failing because they used 75W90?

 

[Rhinebeck01]

Well, this thread reminded me I needed to go to Amazon and order another Valvoline Flexfill SAE 75W-140 Full Synthetic Gear Oil 1 QT, Case of 4 for the next diff fluid change.

Cost just now, with tax applied, ended up being about $15.50 per bag.

https://www.amazon.com/gp/product/B08KB5LTJM/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8psc=1

 

[Remorseless]

Does anyone have any evidence of gears/bearings in a JL/JT failing because they used 75W90?

With the number of folks who buy a Jeep and probably never ever touch their diff fluid, I'd be willing to bet that if 75w90 was causing long term issues we'd see a lot more grenaded diffs given that 75w90 is what comes factory.

 

[BDinTX]

With the number of folks who buy a Jeep and probably never ever touch their diff fluid, I'd be willing to bet that if 75w90 was causing long term issues we'd see a lot more grenaded diffs given that 75w90 is what comes factory.

Wonder what the number of people with failed sensors have never changed their diff fluid from factory fill...

 

[Remorseless]

Wonder what the number of people with failed sensors have never changed their diff fluid from factory fill...

That'd be interesting to see the data on. I'd honestly love to see an engineering teardown of a failed sensor. Heat, vibration, oil intrusion, oil intrusion with suspended metals, degrading circuitry/solder - so many things that those sensors are sensitive to happen in those diffs.

 

[BDinTX]

Ya I agree. I changed my diff oil relatively early and have to admit the only other time I have done this was on my first car decades ago.

So I don't know what would be considered normal but I did notice when I held a magnet next to the oil, the oil pulled strongly towards the magnet. I'm pretty sure that is an indication of suspended metal.

Unrelated side note: Your avatar pic cracks me up.

 

[Remorseless]

Ya I agree. I changed my diff oil relatively early and have to admit the only other time I have done this was on my first car decades ago.

So I don't know what would be considered normal but I did notice when I held a magnet next to the oil, the oil pulled strongly towards the magnet. I'm pretty sure that is an indication of suspended metal.

Unrelated side note: Your avatar pic cracks me up.

Yeah, gears breaking in do tend to shed some steel. Lots of "fuzz". That's why I like to change my gear oil at ~1k mi on a new vehicle. At least ones where it's decently accessible lol.

The avatar is Brian Regan, comedian. The boys and I at work use a gif of one of his standups to mercilessly mock ourselves and derpy coworkers in one of our side chats and it's stuck with me. Motion makes it better.

 

[BDinTX]

and derpy coworkers

good idea! stealing it

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