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75w140 in both front and rear axles - Rubicon

andrei

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Anyone know the fill capacities for both the front and rear diff? I'm seeing 4 quarts total should get you full for the front and rear. Thoughts?
Rubi axles took 3 in total. A little more than 1.5 for rear and little less than 1.5 for front, both until it started coming out of fill hole.
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CarbonSteel

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Mine dropped an average of ~1 mpg after switching.
Jeep Wrangler JL 75w140 in both front and rear axles - Rubicon ахах


Your right foot, a head wind, heavier load, or driving a higher speeds will impact MPG more than a viscosity change ever will.

I'm sure you tested this theory in a controlled environment and repeated it thousands of times to remove all variables, right?
 

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I have the electronic lockers 210 front and 220 ELD rear. (Correct me if I’m weonf

I’m planning to use Valvoline 75w140 in both my front and rear differentials after reading just about every thread and post on this forum. From what I can tell this recommended weight came directly from Dana themselves.

Aside from Valvoline, is there a better gear oil brand recommendation?

Valvoline FlexFill Full Synthetic SAE 75W-140 Gear Oil 1 QT Pouch https://a.co/d/7OVwzVG
Mobil 1 104361 75W-90 Synthetic Gear Lube
 

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I live where it’s a bit colder so I run 75-90 Amsoil severe gear.
 

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Kracka

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I'm a fan of Redline so that's what I run (factory spec 75W-85 to be exact)... but... you really can't go wrong with any of the brands mentioned here. If you want cheap & convenient, then Valvoline is the easy choice.

If you're concerned a 75W-140 will be too thick for your needs, both Redline and Amsoil offer a 75W-110 (or you can blend your own by mixing Valvoline 75W-90 & -140).
 

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bobholthaus

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Guys: Reviving this thread. Someone told me recently that 75W140 fluid gets too thick in the cold winter weather of Missouri (high today in the 20s). Any thoughts on this? Shall I run different weights at differnt times of the year? And thank you for the Dana specs; that's interesting that they recommend the heavier weight both front and rear.
 

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Guys: Reviving this thread. Someone told me recently that 75W140 fluid gets too thick in the cold winter weather of Missouri (high today in the 20s). Any thoughts on this? Shall I run different weights at differnt times of the year? And thank you for the Dana specs; that's interesting that they recommend the heavier weight both front and rear.
Refer to the two posts above yours.
 

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bobholthaus

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Refer to the two posts above yours.
Duh, sorry about that. Thank you!

I just googled it, and this is what came up:


Yes, 75W140 differential fluid can be considered too thick for very cold weather conditions due to its high viscosity rating, particularly the "140" part which indicates its thickness at high temperatures, potentially making it sluggish and less effective in extreme cold.

Key points to remember:
  • "W" rating indicates cold flow:
    The "75W" part of the designation refers to the oil's flowability in cold temperatures, and while 75W is generally considered suitable for most cold climates, the high "140" viscosity can still be problematic in very low temperatures.

  • Potential issues with thick diff fluid in cold weather:
    • Slow gear engagement: The thick oil may take longer to circulate and reach all the gears, leading to sluggish shifting or engagement issues.

    • Increased wear: If the oil is too thick, it may not adequately lubricate the gears, potentially causing increased wear.

What to do in cold weather:
  • Check your vehicle manufacturer's recommendations:
    Always consult your car manual for the most suitable differential fluid viscosity based on your climate.

  • Consider a lighter weight oil:
    If you live in an area with extremely cold winters, a lighter weight gear oil like a 75W-90 might be a better option.
 

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I'd really consider it a problem in like, Alaska or something similar. Where you're at you get cold snaps, but not enough to take this into consideration. If it's super cold out just don't put a ton of load on it when you start out, just like you wouldn't go WOT on a cold engine. It won't take long for the diff to warm up, mile or two maybe.
 

bobholthaus

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I'd really consider it a problem in like, Alaska or something similar. Where you're at you get cold snaps, but not enough to take this into consideration. If it's super cold out just don't put a ton of load on it when you start out, just like you wouldn't go WOT on a cold engine. It won't take long for the diff to warm up, mile or two maybe.
Makes total sense!

I can't find a Mopar part number for 75W140 that works at my local discount dealer place. Anyone have this number? I'm under an 8 year 125k mile Mopar warranty, so I'm going to continue to use Mopar fluids so they can never claim that I did something incorrectly. I could totally see them saying that.
 

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Was there something else about running different weight in the rear when towing. I think, I went 90 in the front and 140 in the rear? Obviously the same in both is easier.
 

bobholthaus

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Was there something else about running different weight in the rear when towing. I think, I went 90 in the front and 140 in the rear? Obviously the same in both is easier.
I don't understand your question. Please expand?
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