Gear oil change now, or wait?

[NWJeepr]

2023 Rubicon XR with 1300 miles, factory gear oil. Headed to Moab shortly...if it's not broken in yet, it will be!

I've got a couple of pouches of 75w140 ready to be swapped in (recommended per Dana for the M210/M220). Would you swap the factory fluid before or after the trip?

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[kah.mun.rah]

IMO I would wait until after. @CarbonSteel is the oil guru and can probably chime in.

 

[JT1]

2023 Rubicon XR with 1300 miles, factory gear oil. Headed to Moab shortly...if it's not broken in yet, it will be!

I've got a couple of pouches of 75w140 ready to be swapped in (recommended per Dana for the M210/M220). Would you swap the factory fluid before or after the trip?

Swap it now and pot your locker sensors while you're in there.

 

[Maverick909]

i would wait until after. no reason to swap your gear oil at 1300miles. If i remember correctly i waited until 15K to do my oil change. hell I dont think my work truck rear end gear oil has ever been changed in 160K miles. still all good.

 

[Valpo Jeep]

Speculative percentages here.

65% or more of owners would not change the gear oil until 30,000 if at all.

30% would change it at 30,000 miles only because they were in for an oil change and the service advisor talked them into it.

4% view it as cheap insurance and would change it out at your mileage.

Maybe 1% would change before and after the trip.

None of them are wrong but yet none of them are right either. Ideally you would run a Blackstone analysis to determine if it’s really needed but the problem with that is the cost is basically the same as doing the job yourself.

2 summers ago I changed the differential oil in our Audi at 204,000 miles, see pic below. It was dark but flowed and smelled like new oil. Differential oil lasts a very long time provided you can keep water out of it.

 

[kah.mun.rah]

Differential oil lasts a very long time provided you can keep water out of it.

This is a good point OP, if you think there is any chance of water crossings on your trip you would be throwing away your money if you change the dif oil before the trip.

 

[CarbonSteel]

I would wait--the axles will not be broken in at that point and will still be producing plenty of wear metals. While it will not hurt to change it now, just know that it will require another oil change (if you want to remove all of the break-in metals).

To my point above, until you see the wear metals "crossover" and an established trend of the axle starting to add more miles for each part per million of iron, it is not fully broken in. At 5K miles, my OEM axle was still producing a large amount of iron, but between 10K and 15K miles, it had reversed that trend was running more miles between PPM of iron.

Most other axles I have experience with complete the cycle sooner (typically broken in before 10K miles), but not always. Of course, this is minutiae for most people but wanted to share anyway.

 

[Da Capt]

I’d wait …. but bring the oil just to have , if at some point u feel u need to change it u can on the fly.

 

[NWJeepr]

Decided to wait until after the trip. The Jeep has 2,000 miles on it now. As expected, there was dark fluid in the rear fluid as the clutches wear in. No chunks, no glitter, just a haze on the fill plug. I refilled the front and rear with 75w-140, and 4oz of limited slip modifier for the rear axle only.

I did check the oil levels front and rear just after taking delivery and the level on both was perfect. By the time I changed it, it had not leaked any and the level was as I remembered from the first check.

Rear (drain pan was completely clean prior to drain):

Front: It actually came out pretty clean with just a little bit of darkness as the bottom of the diff flushed out. The pan was not completely clean after dumping the oil from the rear. Maybe this isn't a great photo, but it does show the front mostly amber/clear, as it should be.

Anyhow, I'm posting this as a reference for if anyone asks if they should change their diff oil in their Rubicon early. Maybe, maybe not...I don't think I would have wanted much longer on the rear. The front would have been fine for many more miles.

---

**Next day edit: So, the Jeep hasn't been moved since refilling the differentials and it occurred to me the lube I used already has LSD additive, duh. Looking up the concentration for Valvoline 75w140 synthetic gear lube it says it has a concentration of approximately 4oz per quart of fluid. At ~1.5 quart oil capacity for the rear diff M220, that should be nearly 6oz of additive already in the fluid. With my additional 4oz I put in, that's almost 10oz of limited slip goo. Waaaay too much.

Now, I've read a lot of threads where it says *no LSD additive needed for Rubicons*. That's not true. We can have open diffs with e-lockers, or we can have LSD diffs, also with an e-locker. Mine has the Trac-Loc LSD *and* e-lockers, so yes, LSD goo is required. This wasn't the case for a long time - in the JK platform, Rubicons weren't available with an LSD for a long time, only e-lockers.

So, I'm going to be draining that this morning and refilling with only gear lube, with the LSD already in it. Dumb mistake, but hey, now that pumpkin is going to be *really* clean inside. If I get any chatter, I can always add more LSD goo.

 

[Gorilla57]

You do NOT have clutches in the Rubicon axles. I’m not sure where you got that info, but it’s wrong.

I’ll tag @chevymitchell and let him explain this fully as he’s done plenty of JL gear swaps and knows all the ins/outs of these axles.

 

[NWJeepr]

You do NOT have clutches in the Rubicon axles. I’m not sure where you got that info, but it’s wrong.

I’ll tag @chevymitchell and let him explain this fully as he’s done plenty of JL gear swaps and knows all the ins/outs of these axles.

The info came from my memory, which appears to be wrong! lol. Thank you for pointing that out. My JK had the anti-spin and I had that Jeep for more than 10 years, so clearly something got crossed up.

I went back and looked at the window sticker and the build sheet, and I could have sworn it had "anti-spin" or "trac-loc" listed somewhere on there, but it doesn't.

The good thing is this changes nothing about the service I performed (however, friction modifier is definitely not necessary!), but I do need to remember to expect open diff behavior when driving in slick conditions...

But why is the fluid so black in the rear diff?

 

[Gorilla57]

Rear diff fluid is darker because it is constantly under load. The fronts aren’t spinning unless you are in 4H or 4Lo. So the rear fluid is getting sheered all the time and the gears are breaking in, letting off gear “dust”.

 

[NWJeepr]

Rear diff fluid is darker because it is constantly under load. The fronts aren’t spinning unless you are in 4H or 4Lo. So the rear fluid is getting sheered all the time and the gears are breaking in, letting off gear “dust”.

I know that part, but that oil only has 2,000 miles on it since new. In a previous Rubicon the rear diff still had amber-colored oil in when I did the first change at 20k.

 

[Gorilla57]

I know that part, but that oil only has 2,000 miles on it since new. In a previous Rubicon the rear diff still had amber-colored oil in when I did the first change at 20k.

It’s been stated on the forums that these new Dana axles run way hotter and produce more gear dust that previous models. Mine looked like yours when I did my first drain, which was 3k miles. Kinda worried me, but everyone on here has seen very similar color and shavings on the drain plug.

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