Rear Differential Fluid Change

[bucktownturtle]

Just changed the rear differential oil. Should I be worried? I figure change it again in a few weeks and see if there is more. There were a couple tiny flakes of metal but mostly just metal paste. It's probably the first time the oil has been been changed and it's got 158k on it.

 

[geanes]

Just changed the rear differential oil. Should I be worried? I figure change it again in a few weeks and see if there is more. There were a couple tiny flakes of metal but mostly just metal paste. It's probably the first time the oil has been been changed and it's got 158k on it.

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Nothing to worry about at all. That's normal to see some shavings or "paste". A problem would be if you saw small "chunks" of metal.

 

[80Kiter]

Just changed the rear differential oil. Should I be worried? I figure change it again in a few weeks and see if there is more. There were a couple tiny flakes of metal but mostly just metal paste. It's probably the first time the oil has been been changed and it's got 158k on it.

View attachment 1734038

View attachment 1734040

Looked just like mine when I changed it @300k - A shop I was working with (East Coast Gear Supply) didn’t seem surprised. I’m no mech so please correct me but If you wanted to be proactive put it up on a lift with someone engaging it in drive and have a trained tech listen to the sounds for anything off. Eventually as was my case the bearings need replacing however my milage is 2x yours.

 

[SWUtah]

I think the first change for the differentials is the most important done at 30,000 miles you get all the break-ins stuff out then it should be smooth sailing

 

[bucktownturtle]

I think the first change for the differentials is the most important done at 30,000 miles you get all the break-ins stuff out then it should be smooth sailing

I agree however with this being a used car, I don't have control over that. Only trying to make right what I can now. I put conventional in this time to flush it out with clean oil. I will change it again in a few weeks and put synthetic. We'll see what the plug looks like then.

 

[Jefferdy]

Just changed my TC and rear diff fluids, front will be done tomorrow. I thought I'd share my thoughts on a transfer pump I used that was a MUCH more positive experience than the soap-dispenser one that I bought at O'Reilly's last time I changed diff/trans fluids!

I used a Lisle Model 17282 Fluid Extractor/Transfer Pump and it worked awesomely! 17282 Fluid Extractor / Transfer Pump | Lisle Corporation I tried doing the ol' upside down bottle thing, and then putting a small section of hose on the bottle tip, but both of those were hassles compared to drawing out the fluid in one big draw and then slowly pumping it into the diff/case on the opposite stroke.

If I get pics figured out, I'll post 'em of my setup. Hopefully this spares your workspace a few cuss words next time you decide to tackle this job!

Glad I did this fluid replacement: truck has 275K miles and I am not sure it's ever been done, by the looks of the fluid that came out...

Lisle Hand Pump

• Jefferdy
• Nov 1, 2018

Lisle Pump at Work

• Jefferdy
• Nov 1, 2018

I had the gear oil bottle in a box with a hole cut out to support it, the inlet tube resting in...

 

[jerryb]

I used that pump today on both diffs and tc, I like it. Kind of spendy but it will last a long time.

 

[OEMGUY0720]

Finally got the time to do the:

~~Front Diff~~

~~Transfer Case~~

~~Rear Differential~~

I cannot find any service records pertaining to a FD/TC/RD change fluid from the previous owners (you be the judge). I noticed the front diff oil and transfer case oil are really dark and smelled burnt, while the rear diff oil is brown in color. Also, I collected no metal shavings. Guessing I dodged a bullet here.

How our diff oils should be:

Posted it here, transfer case and rear diff oil change threads for everyone’s convenience.

 

[Guido02]

If you arent locked, 75w/90 will be fine in all three (front-tc-rear). Mobil1 synthetic is a good option- can be found everywhere.

If you have lockers, heavier weight synthetic is recommended. I’m running Royal Purple syn 85w/140 in my TJM locked rear diff, and M1 75/90 in the TC and Front diff.

Im new to LC’s and this is possibly a stupid question, so does this mean the transfer case and rear diff would have a heavier weight oil in a 98 LC, rear and center lockers? I was going to use Mobil 1 75-90W for everything.

 

[geanes]

Im new to LC’s and this is possibly a stupid question, so does this mean the transfer case and rear diff would have a heavier weight oil in a 98 LC, rear and center lockers? I was going to use Mobil 1 75-90W for everything.

I used Mobil1 75-90 LSD in all three diffs on my 98 LX for years. I had to use the LSD because the early LXs came with an LSD rear. The removal of the LSD for a lock means I don't need the LSD fluid any longer. You should be able to run 75-90 in all 3 diffs on an LC without issue at all.

 

[NicB]

Hi guys, I am in the process of changing rear diff fluid. Two questions. First, a little oil came out of the fill hole when I opened her up (which was a total pain given rust). It’s been about 55k miles since the previous owner had it changed at the dealer, and the fluid is darker than new but not terrible. Should I leave it be or change it? The service schedule doesn’t even call for diff oil to be changed unless you have an LSD or it somehow gets contaminated, so I’m having second thoughts.


Second, as another poster mentioned, there was a brief hiss when I opened the fill bolt. Where is this vent located and how exactly would it get clogged? I’m thinking the hiss is just normal myself.

 

[TexFJ]

Hi guys, I am in the process of changing rear diff fluid. Two questions. First, a little oil came out of the fill hole when I opened her up (which was a total pain given rust). It’s been about 55k miles since the previous owner had it changed at the dealer, and the fluid is darker than new but not terrible. Should I leave it be or change it? The service schedule doesn’t even call for diff oil to be changed unless you have an LSD or it somehow gets contaminated, so I’m having second thoughts.


Second, as another poster mentioned, there was a brief hiss when I opened the fill bolt. Where is this vent located and how exactly would it get clogged? I’m thinking the hiss is just normal myself.

I would recommend changing the oil. Also the "hiss" is probably due to a clogged breather valve. Disconnect the breather hose from the axle and blow pressurized air through the hose. It should unclog and blow a bunch of dirt out.

 

[NicB]

I’m planning to put in Mobil 1 synthetic 75w-90 in the diffs and transfer case. Is there any concern installing synthetic where previously it was likely conventional/mineral? I imagine it’s okay but double checking.

 

[geanes]

I’m planning to put in Mobil 1 synthetic 75w-90 in the diffs and transfer case. Is there any concern installing synthetic where previously it was likely conventional/mineral? I imagine it’s okay but double checking.

You'll be fine. Just confirm if you have an LSD rear (98-99 LX did). If you have an LSD or a locker, 75w90 LS fluid is what you'll need. Honestly, that's what I'd use anyway as it's "universal". Can't use non-LS fluid in a locked or LSD equipped diff. Anyway, easy enough job to do. Undo the FILL plug on top first. Then, undo the drain plug. ALWAYS in that order. After driving for a few days, undo the fill plug on the rear and use your pinky finger to check the level (on a flat surface). As you drive, the fluid in the rear will work it's way into the axle and the level will drop just a tad. Top off just enough such that the fluid almost comes out of the fill hole. That's the way I was taught by the guys at LCS here in Austin.

 

[NicB]

Yea, I’ve already loosened the fill plug. It was a bear. Just haven’t had time to drain and refill yetf. I was a bit surprised about a cup of fluid drained out of the fill bolt when I opened it. My garage is pretty dang flat, so not sure why that would be. I do not have an LSD to my knowledge. My truck is an ‘02 and the code in my door label does not indicate LSD, nor do I have a sticker in the diff itself.

 

[TexFJ]

Well I changed fluids on on my 2000 LX yesterday and I grabbed my stock of FJ62 fluids accidentally. Basically filled 80W90 in my TC. I'm not worried about NOT putting in75W90 in there as they're gears. Although it has a locker, it's more pressure but lower gear rotation. Non Synthetic so I'll have to change it sooner.

@NicB, I'm going to assume the PO filled it on a downward slope. Before my TC rebuild on my 62, I was seeing flow from TC to Tranny, but not the other way around. Assuming same could be said for 100 series.

 

[shiretowndown]

So is the grease that I see leaking at CV boots from my front differential? Or is the source of this grease completely different?

 

[NicB]

My hunch is that is grease from a leaky CV boot.

 

[shiretowndown]

Changed my rear diff fluid last night. All went well and looked normal except that that circular piece on the magnetic drain plug.

I plan to clean it and look at it more in depth this evening but it’s perfectly circular. Looks foreign.

 

[OEMGUY0720]

Changed my rear diff fluid last night. All went well and looked normal except that that circular piece on the magnetic drain plug.

I plan to clean it and look at it more in depth this evening but it’s perfectly circular. Looks foreign.
View attachment 2388435

hopefully it’s not a part of the ring or pinion gear. No symptoms like clunk when you accelerate?