Differential oil

[Tncdrew]

Both of the gear oil viscosity numbers discussed in this thread will work, however,
what I said in post #14 kind of sums it up.

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[g2020]

I will add to my guidance on differential fluid and edit my earlier posts in this thread. Thanks to CarbonSteel for providing the docs and Tncdrew for summing it up.

Additional Guidance

• With some important exceptions, Jeep recommends SAE 75W-85 gear oil for fuel economy. For normal driving, this is acceptable.
• For operation under severe conditions (off-road) or heavy loads (trailer towing), be aware that Dana, the manufacturer of the differential/axle, specifies SAE 75W-140 for rebuilds in all cases. Word choice aside ("Rebuild Specification" instead of "Axle Specification"), Dana's recommendation is for durability & longevity.
• The use of SAE 75W-140 will not harm either differential; in fact, this thicker grade offers more protection against wear & tear.
• Reminder: Friction modifier is required for Trac-Lok limited slip (LS) anti-spin rear differential

References in This Thread

Post #19: Links to Dana docs; the Rebuild Specifications are for rebuilds, but this could reasonably apply to new if Dana said the word
Post #25: My response: As a rule, Jeep recommends 75W-85 for stock/OEM builds; the exception in the owner's manual is 75W-140 for the rear differential on vehicles with Sales Code DRZ; in the internal dealer spec sheet, Jeep recommends 75W-140 for the rear differential in a Gladiator (JT) with a Trailer Tow Package
Post #27: Jeep (not Dana) pays for differential warranty repairs
Post #28: Lube level (not overfilled or underfilled) is critical
Post #30: Jeep drivetrain warranty coverage ends after 60,000 miles; 75W-140 will improve differential longevity (slower wear & tear); approving 75W-140 for any (more demanding) application is silent/tacit approval for all applications
Post #14 & #31: Dana/Spicer is concerned with durability/longevity, Jeep is concerned with fuel economy

 

[CarbonSteel]

References in This Thread

Post #19: Links to Dana docs; the Rebuild Specifications are for rebuilds, but this could reasonably apply to new if Dana said the word
Post #25: My response: As a rule, Jeep recommends 75W-85 for stock/OEM builds; the exception in the owner's manual is 75W-140 for the rear differential on vehicles with Sales Code DRZ; in the internal dealer spec sheet, Jeep recommends 75W-140 for the rear differential in a Gladiator (JT) with a Trailer Tow Package
Post #27: Jeep (not Dana) pays for differential warranty repairs
Post #28: Lube level (not overfilled or underfilled) is critical
Post #30: Jeep drivetrain warranty coverage ends after 60,000 miles; 75W-140 will improve differential longevity (slower wear & tear); approving 75W-140 for any (more demanding) application is silent/tacit approval for all applications
Post #14 & #31: Dana/Spicer is concerned with durability/longevity, Jeep is concerned with fuel economy

For #19 the only axle that Dana supplies new to the market that a consumer can buy are the UD axles so I would not expect to see them state "new" versus "rebuild" given that with the UD axle comes the documentation that specifies 75W-140. There have been a few on the forum buy UD axles and have commented that it is 75W-140.

Jeep and Ford are two of the largest purchasers of Mxxx axles, so one can easily assume the only fluid recommendations for "new" axles will come from either of those versus Dana themselves.

 

[g2020]

For #19 the only axle that Dana supplies new to the market that a consumer can buy are the UD axles so I would not expect to see them state "new" versus "rebuild" given that with the UD axle comes the documentation that specifies 75W-140. There have been a few on the forum buy UD axles and have commented that it is 75W-140.

Jeep and Ford are two of the largest purchasers of Mxxx axles, so one can easily assume the only fluid recommendations for "new" axles will come from either of those versus Dana themselves.

Thanks for clarifying. The convincing part is that Dana repeatedly recommends 75W-140 for rebuilds. They tell it like it is without dancing around environmental standards.

 

[Boatbuilder88]

I bought Valvoline 75W90 w/ limited slip additive.

• M186 front axle
• M220 rear axle / LSD
• No towing. Little off-roading. Mostly pavement driving

 

[Vinman]

Make it easy - you can use 75w 140 for both front and rear. Absolutely zero issues if you go that route.

Exactly what I have done with zero problems

 

[Rhinebeck01]

A real shame when a forum member uses an AI Text Generator to generate posts in forum threads like this.

Reality is the guy doing this is undoubtedly clueless himself in regard to the JL, oil filters, etc..

The AI Text Generator gets the info, and it is spewed here. Much of the information is information gleaned from say Stellantis literature and not say from the Manufacturer DANA, etc..

Unfortunately, there's lots of misinformation in these AI Text Generated posts....

Anyway, you guys/gals doing research on diff fluid changes, oil changes, oil filters, ect., do be careful what you you leave the forum with information wise.

 

[NWJeepr]

Somewhat related...I went looking for fluid spec for the Meritor 24k rear axle in our motorhome. It's a 4.89 and it requires 75w90 (like 3 gallons of it...). The rig is capable of 60k gross combined...a little stunned that a more robust gear oil isn't used. Looking up other axle spec used on heavy duty tractors, all the big makers basically specify the same 75w90, and those are on Class 8 trucks up to 105,500 gross combined.

Is 75w90 really that inadequate for a little tiny D44?

 

[azwjowner]

Somewhat related...I went looking for fluid spec for the Meritor 24k rear axle in our motorhome. It's a 4.89 and it requires 75w90 (like 3 gallons of it...). The rig is capable of 60k gross combined...a little stunned that a more robust gear oil isn't used. Looking up other axle spec used on heavy duty tractors, all the big makers basically specify the same 75w90, and those are on Class 8 trucks up to 105,500 gross combined.

Is 75w90 really that inadequate for a little tiny D44?

There's a big difference between 12 quarts of gear oil and 2 quarts in our axles for heat, longevity, etc.

 

[NWJeepr]

There's a big difference between 12 quarts of gear oil and 2 quarts in our axles for heat, longevity, etc.

That's what I'm getting at, though. How different are the temps between something like a Jeep diff under load versus a medium/heavy truck differential. The difference in fill volume is apparent, but does that just equate to more frequent recommended changes for a smaller diff, not necessarily a heavier oil.

 

[azwjowner]

That's what I'm getting at, though. How different are the temps between something like a Jeep diff under load versus a medium/heavy truck differential. The difference in fill volume is apparent, but does that just equate to more frequent recommended changes for a smaller diff, not necessarily a heavier oil.

It's a good question. I suppose measuring oil temperature in each would answer the question of what exactly the purpose of the extra volume is.

 

[g2020]

This is a reply to post #37:

So you think I'm using AI? Is your next claim going to be that I work for a Sasquatch task force at Area 51?

You forgot to mention that you have stalked me on this site and attempted to stalk me on the Gladiator sister site. Nobody cares, but subtract your 10 Haha or Sad reactions from my reaction score on this site. Also, I happened to be looking at my post, on the Gladiator site, at the moment that you were trying to stalk it next. Your emoji showed up and then got removed on the next refresh. Unlike this site, the Gladiator site has two-way Ignoring.

Attempting to stamp out facts with graffiti is an interesting mode of attack. Is there an emoji that can magically (as in "poof") cover damage to other parts for a MOPAR oil filter used in a DIY job?

I contacted you by DM after your first stalk and told you that I would block you if you did it again. Since you were the first person I had ever Ignored, I didn't know that this site doesn't have two-way Ignoring. Until it does, I will receive any future stalking attacks by you as an invitation to review your posts. Whether I comment on your treasure trove of content will be up to you.

Stalking is just weird.

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