Gear Oil Weight Clarification

[MercMan54]

Hello,

I have 2021 Gladiator Sport S, 3.6L Pentastar, and the tow package (*Not max tow).

I need a clarification on which gear oil to use for rear diff. The manual states to use Mopar 75W-85 however I have seen on multiple forums to use 75W-140 if you have the tow package. Is that tow package or max tow?

I checked mine out of curiosity. Front is honey colored - looks brand new. Rear is very dark after only 12k miles. I do have to sink my truck pretty deep to launch boat so not sure how much that is contributing but I'm going to change rear fluid.

Just curious if forum has any recommendations on oil weight?

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[bleda2002]

Gear oil will turn dark very quickly, not a big deal.

If you tow a lot or off road a lot Dana recommends 75w140. If not the factory recommendation is also fine.

 

[ShadowsPapa]

Hello,

I have 2021 Gladiator Sport S, 3.6L Pentastar, and the tow package (*Not max tow).

I need a clarification on which gear oil to use for rear diff. The manual states to use Mopar 75W-85 however I have seen on multiple forums to use 75W-140 if you have the tow package. Is that tow package or max tow?

I checked mine out of curiosity. Front is honey colored - looks brand new. Rear is very dark after only 12k miles. I do have to sink my truck pretty deep to launch boat so not sure how much that is contributing but I'm going to change rear fluid.

Just curious if forum has any recommendations on oil weight?

ignore colors of most lubes - EP (hypoid gear lube) is no exception.
Boat launching is nothing to do with it.
Otherwise, what's already been said.

 

[Badunit]

That's 12K miles of the rear propelling the vehicle down the road vs the front just going along for the ride (except when in 4wd). There are more wear particles from the gears breaking in. Water intrusion would make it look kinda like a milkshake.

 

[ShadowsPapa]

Water intrusion would make it look kinda like a milkshake.

Yeah, water in the lube would form an emulsion that looked like a grossly over-priced bad cup of something from Starbucks.

 

[Max-t]

If you’re dealing with factory parts use factory indicated lubes.

Anyone my age or older than me (and their protégées) that grew up on conventional oils and winter vs summer specs etc thinks they know some secret.

 

[ShadowsPapa]

If you’re dealing with factory parts use factory indicated lubes.

The problem is - which factory? Or more properly, which recommendation?
Jeep tech docs?
Jeep's owner manual?

Either obviously works, but the tech documents consumers don't normally see is different than "the book". In the end it shouldn't really matter - I've pulled some hellish loads on what the owner's manual recommends - as long as that's the minimum.

This is nothing to do with oils or winter/summer specs. Not sure what that's got to do with it or anything, actually

 

[Hootbro]

There is nothing wrong with following the owners manual of using the 75W-85 grade gear oil. Most people though will use a quality 75W-90 synthetic as that is a way easier to find and many times a less costly alternative.

That being said, Chrysler Tech Authority referencing the tow package and DANA rebuild tech data call out using 75W-140 grade gear oil.

As to what a recommendation would be, I would leave that up to you. There is reliable reference data supporting either grade weights.

 

[bd100]

There is nothing wrong with following the owners manual of using the 75W-85 grade gear oil.

That being said, Chrysler Tech Authority referencing the tow package and DANA rebuild tech data call out using 75W-140 grade gear oil.

Does anyone know: if ordered with the tow package does it come from the factory with 85 or 140?

If it comes with 85, then I wish the owner's manual had a warning to change to 140 if often towing or offroad, but I haven't found such a warning.

 

[smlobx]

There is nothing wrong with following the owners manual of using the 75W-85 grade gear oil. Most people though will use a quality 75W-90 synthetic as that is a way easier to find and many times a less costly alternative.

That being said, Chrysler Tech Authority referencing the tow package and DANA rebuild tech data call out using 75W-140 grade gear oil.

As to what a recommendation would be, I would leave that up to you. There is reliable reference data supporting either grade weights.

In looking at both documents if you have the tow package then you use the 75W-140 plus a friction modifier if called for.

 

[Hootbro]

Does anyone know: if ordered with the tow package does it come from the factory with 85 or 140?

If it comes with 85, then I wish the owner's manual had a warning to change to 140 if often towing or offroad, but I haven't found such a warning.

I do not think anyone knows for certain as differential gear oil analysis for a Gladiator or most any other vehicle is hard to come by.

My speculative guess it is probably 75W-85 grade out of the factory regardless to meet EPA MPG requirements they certify the vehicle at. This does not mean it is an inferior weight grade, just what is used by the OEM (Stellantis) to meet their gov. regulatory requirements.

Same question has been brought up before in other threads on the disconnect between service data and the owners manual. I think people tend to look at is a either right/wrong discussion instead of seeing it as a either/or.

https://www.jeepgladiatorforum.com/forum/threads/differential-axle-fluid.41177/

 

[ShadowsPapa]

I do not think anyone knows for certain as differential gear oil analysis for a Gladiator or most any other vehicle is hard to come by.

My speculative guess it is probably 75W-85 grade out of the factory regardless to meet EPA MPG requirements they certify the vehicle at. This does not mean it is an inferior weight grade, just what is used by the OEM (Stellantis) to meet their gov. regulatory requirements.

Same question has been brought up before in other threads on the disconnect between service data and the owners manual. I think people tend to look at is a either right/wrong discussion instead of seeing it as a either/or.

https://www.jeepgladiatorforum.com/forum/threads/differential-axle-fluid.41177/

I think the fact that the owners manual states the lower viscosity tells us that the large majority of Jeep owners who do their own work go back to that viscosity as specified in the owners' manual. And we don't see dozens of posts saying it's not working out. In fact, it's not common to see failures, especially related to lighter lube.
It's a given that the majority of Jeep owners are not members of this or the Wrangler forums, and many do their own work on something so very simple - and of those, you could bet they are using that book that came with the Jeep to tell them what to put back in.
Only those who are in forums and do searches that lead them to posts as have been found by some here will even know there's another choice.
Logic would say - it won't matter, the factory likely uses the lighter lube, and almost all who do their own service will be using it, and you don't see widespread failures.
It's an ant hill that's been bulldozed into a burial mound and quickly becomes a mountain in Jeep forums - and it shouldn't even be the ant hill.

This is the 2022 book - DRE is the standard width axle as under Overland, Sport, Sport S without MAX TOW, etc. whiile DRF is the wider axle as under Rubicon, Sport WITH MAX TOW and so on.
So they are saying it's not based on tow package nor is it based on axle width or ratio. They are saying any M220 (which is the JT rear axle assy), wide or not, tow or not, same thing.
Since it's part of the power train, one could think - hey, if it's used for MAX TOW towing or Rubicon towing up to 7,000 pounds and there was a problem with the 75w85 - why put it in from the factory?

Lots of ways to look at it.

 

[ShadowsPapa]

Does anyone know: if ordered with the tow package does it come from the factory with 85 or 140?

If it comes with 85, then I wish the owner's manual had a warning to change to 140 if often towing or offroad, but I haven't found such a warning.

Sort of a contradiction there - if you buy one with the tow package or even max tow, they gotta assume that you are going to tow with it. To suggest an owner change gear lube if they plan on towing is going to get them into a legal pickle and cause a big ruckus. Buy our truck, it's got a tow package but hey, if you are going to tow you need to pay us to switch fluid? And no, they can NOT assume an owner would do such a thing themselves, in fact they must assume the owner will not do that sort of work. Most vehicle buyers/owners, yes, including Jeep, don't do their own work of that type. (if they did shops wouldn't be swamped)
So to say:
buy it, it's best in class towing, and you've got the tow package but now you must pay to have the lube changed so you can tow!
Wow.
It's an off-road vehicle - look, Rubicon comes with more clearance, sway bar disconnect, locking axles, low ratio transfer case, it's ready to go, but if you plan on actually using it, ooops, you need to get that lube changed!
And for used vehicles - how the @#$% would anyone know what's in it! you'd have to assume it's not been changed and you buy this nice used truck - and now you must pay someone to change the lube just to be sure as you plan on towing?

To me, all of the above shows the owners' manual suggestion is just fine.
Really think about it - and know that most either wouldn't know to do that, and most won't be doing it themselves. Heck, even forum members come in to ask how to change the lube.
That's nothing against them, that's not belittling them in ANY way, it's just proving my point that most owners will not only not know or be able to do it, they won't be aware.
Contrary to the he-man Jeep forum member's assumptions and views of how Jeep owners should be - because they are and they are the proof, most owners don't do that sort of work, many don't know how, many don't want to. (otherwise dealers couldn't sell brand new jeeps maxed out with aftermarket stuff ready to drive off the lot. )

 

[MercMan54]

Thank you all for input & discussion. Oil is not milky so do not believe there is any significant water intrusion. I decided to change it out for piece of mind - went with ordering Mopar 75W-85 (no additive - no LSD) as I don't do a ton of towing (no pun intended).

 

[ShadowsPapa]

Thank you all for input & discussion. Oil is not milky so do not believe there is any significant water intrusion. I decided to change it out for piece of mind - went with ordering Mopar 75W-85 (no additive - no LSD) as I don't do a ton of towing (no pun intended).

It's rated at over 2 ton of towing so you are ok LOL

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