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Differential Oil Change

9K views 26 replies 5 participants last post by  TheLaSwamp 
#1 ·
I just changed the rear differential oil for the first time. It really was a piece of cake. I installed the axle breather mod and decided to just go ahead and change the oil too. I drove about 10 miles so as to heat the oil a bit and get some of the metal shavings into the oil.

The OEM check valve seemed to be functioning properly. There was no sound of air streaming in or out of the axle when I removed the valve. Other than smelling as bad as everyone says it does, the oil, otherwise, looked good. No signs of water intrusion into the axle. There were some metal shavings on the drain plug, but not much. The oil was clear enough for me to be able to see the bottom of the drain pan. The oil had about 20k miles on it. This is my third axle, the first two having been replaced under warranty for making lots of noise at speed. I take it the clear oil is a good sign? I was half-expecting the milkshake from many of the posts here.

I filled the pumpkin with Mobil-1 75w-140, so I am hoping I am good to go for a while. Was there anything else I needed to be on the lookout for?
 
#2 ·
Keep an eye on the inboard side of the brakes for leaking axle seals. Sounds like your oil was in good shape. What did you use on the threads of the plugs? I started out using RTV but switched to Teflon tape. It's much easier to use and haven't had any leaks.
 
#4 ·
I looked around while I was under the truck, but I didn't see anything that looked like oil leaking. I was pretty relieved when I removed the OEM vent and it did not seem to be blocked. I used Teflon tape for both plugs on the pumpkin, and on the fitting for the vent mod. I haven't had a chance to drive the truck much since yesterday, but I did take it to the store down the road. It felt smooth and quiet.
 
#3 ·
Should be good for at least 50k. FYI that's not actually a check valve, it's just a fitting with a dust cap on it.
 
#7 ·
I've had a chance to drive a bit since I did the diff oil change. The truck feels normal around town, but when I get up to speed, it feels like... I don't know... like it's dragging a bit. The engine seems to have to work a bit harder to get up to speed and keep it. I don't know if it's my imagination. I guess the new oil is thicker, but it's just a little over two quarts. I can't imagine it would actually make any difference that could be felt.

Or can it?
 
#14 ·
I'm pretty sure I have my original 2.94:1 axle. I tore it apart and replaced the pinion bearings at about 85,000 miles. Since then it's been great. I'm now at 113,000.
Unfortunately I live in New York State, so the rust will be getting to it before the mileage I'm sure.
 
#16 ·
The original spec that called for 80w-90 has been superseded. 75w-140 is is the new specification. My '07 came with 75w-140 in the rear axle.
 
#18 ·
Got under the truck yesterday to check to see if everything was okay since installing the axle vent and changing the differential oil. I had to Goggle pics of the leaking axle gaskets so I'd know what it looks like. The pics all showed obvious oil leaks on the back sides of the rear brake shields. Both of mine were clean. So, hoping I'm good to go, at least for the time being.
 
#20 ·
There's no reason not to use 80w 90, considering every other axle since the beginning of time has used it. I firmly believe Nissan changed their spec in hopes of avoiding a few extra warranty claims.
That being said, I still prefer 85/140, being free and all. My truck lives in New York, and gets used!
 
#22 ·
I agree. From what I understand, the early differentials were overheating, cooking the oil and the gears. I'm sure that played a role on the axle seals failing, too. Although it is said that many of the axles were shipped under-filled with oil, I wonder if it was also other factors as well. Nissan switched to the finned rear cover and started using heavier oil. I don't know if Nissan knew that would fix the problem or if they were just spitballing solutions. They didn't want to have to redesign the rear axle until the next generation. When I pulled my oil at around 20k miles, it looked good. It was clearly not burnt, and there was no abnormal amount of metal in it. I don't do any towing, though, and my morning commute is relaxed. I'm about as easy on the truck as it's possible to be on a motor vehicle.
 
#21 ·
Nissan isn't the only one using that weight in the rear differential. The '04 spec was 80w-90 (or something close to that) until Nissan revised that to use the heavier weight.
 
#23 ·
I had a chance to take the Titan on a short road trip yesterday. Once the differential oil heated up, I notice that the rear gear moan came back. And no, it was not from my girlfriend in the back seat.

I was hoping it was tire noise, but it was clearly not tire noise. I would speed up to about 75 mph and then let off the throttle. Once the truck coasted down to 70 mph, there was a fairly noticeable moaning sound coming from the rear axle, all the way down to 60 mph, where the moaning fades. I had hoped the fresh gear oil would have silenced the gear noise, but clearly it did not. The muffler is too loud on throttle to tell if the moaning is happening on acceleration from 60 to 70 mph. I could not create the sound when the gear oil was cold, only when it was heated up. The gear oil change did not reveal a lot of metal shavings, but with these axles, who knows.

Lube, what say you? Anything to worry about?
 
#24 ·
You probably have a very small amount of play in the pinion and/or carrier bearings. It is not something to worry about, but should be addressed within the next 10,000 miles or so.
Hopefully its just your carrier bearings, which means you can make a simple backlash adjustment to correct.
 
#25 · (Edited)
The problem is that my truck is still under warranty. I can only take it to the dealer, and they don't have anyone there that knows how to make adjustments to the differential. They literally only know how to replace the entire axle under warranty. I still have another year and 35k miles of warranty left. I sent a letter to the dealer general manager advising him that the axles were not set properly from the Dana factory, but I don't think he had any idea what to do about it, either. This is a Nissan problem and I suspect they just want to wash their hands of the entire embarrassing mess at this point.

It's maddening, because if you're right, this is a simple fix. But the warranty won't allow me to let anyone else touch the thing. I'm not sure what to do in this case.

ETA: This is the ultimate Catch-22. The adjustment has to be made under warranty, but the warranty won't allow me to make the adjustment. Bureaucracy at its finest.
 
#26 ·
If this is the case:

who exactly is going to know???

the dealer techs wouldn`t see an adjustment in thousands of an inch! they wouldn`t see or recognize anything.

If you have a repair shop who knows these axles and "they" do a proper job including using the same sealer on the diff cover, how will Nissan know? other than you not calling them to replace the axle assembly.:dunno:
 
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