Changing diff fluids and had a couple questions... (1 Viewer)

[OffRoadRN]

I am going to change out the oil in the front and rear diffs, as well as the transfer case. Is there a center differential to drain too, or is that just a locking mechanism that goes in between the front and rear?

As far as oil goes, I saw one thread where someone recommended running some cheap oil for a while and then switching it again for nice synthetic stuff if the service history for the diffs isn't known. Is this a good idea or should I just put the good stuff in right from the beginning? My truck has 245k on it and I obviously want it to last much longer.

 

[nissanh]

I am going to change out the oil in the front and rear diffs, as well as the transfer case. Is there a center differential to drain too, or is that just a locking mechanism that goes in between the front and rear?

As far as oil goes, I saw one thread where someone recommended running some cheap oil for a while and then switching it again for nice synthetic stuff if the service history for the diffs isn't known. Is this a good idea or should I just put the good stuff in right from the beginning? My truck has 245k on it and I obviously want it to last much longer.

The transfercase and center diff are all in one unit. Jut don't over tighten the bolt on transfercase housing. It is made out of an aluminum alloy and can crack. Use new crush washers. Just drain and add new fluid. IF this is the first time you are doing it, check the diff breathers. Front diff breather is located on frame below the P/S fluid reservoir and rear is mounted on to the cross member between the rear axle and spare wheel.

 

[AlpineAccess]

Transfer case has it's own drain and fill plug as does the front diff.

DIY Transfer Case Fluid Change How-To

A few weeks ago I decided it was time to change the transfer case (T-case) fluid and starting doing a bunch of research here on Mud. I found lots of good info in lots of different threads so I thought I would document the work and put everything into one thread. It is definitely a super easy...

forum.ih8mud.com

 

[shtbrwn86]

Transfer case has it's own drain and fill plug as does the front diff.

DIY Transfer Case Fluid Change How-To

A few weeks ago I decided it was time to change the transfer case (T-case) fluid and starting doing a bunch of research here on Mud. I found lots of good info in lots of different threads so I thought I would document the work and put everything into one thread. It is definitely a super easy...

forum.ih8mud.com

Have fun with the front diff

jokes aside, it's not THAT bad. Just be prepared for those bolts to be on there TIGHT! There are numerous posts on here about how to refill the diff - going in from the top, etc, but I found the standard fluid pump on a quart bottle worked fine and was easy to fill the diff...

 

[Hokie LX]

Each diff and the t-case have a fill and a drain plug. Open the top fill plug FIRST, then once out, remove the drain plug. This is so you don't realize after you have drained all of your fluid out that it may be seized.

I run Amsoil Severe Gear 75W-90 in the diffs and Amsoil Manual Transmission and Transaxle 75W-90 oil in my transfer case. You can likely run cheaper fluids with no issues like Valvoline or Redline or the like. I'd say just go with the oil of choice from the start.

Use a torque wrench to tighten the plugs back down when you're done.
- F&R Diff - 36 ft-lbs for the plugs
- Transfer case - 27 ft-lbs for the plugs

Get new washers for the drain and fill plugs and make sure they're correct. Diffs get steel crush washers, t-case gets aluminum flat washers.

 

[yackowski]

Whatever brand you use- I sure liked the easy pour bags I used on this latest one. No pump, no mess, no hassle- Fantastic

 

[planomateo]

Whatever brand you use- I sure liked the easy pour bags I used on this latest one. No pump, no mess, no hassle- Fantastic

A converted pressurized bug sprayer works even better

 

[2001LC]

I was searching for the differential shop mention in mud somewhere. The one that recommends, not using synthetic gear lubes in diffs & transfer. With the exception of Mobil One gear lube. Any have there name or better yet can post a link here?

 

[shtbrwn86]

I was searching for the differential shop mention in mud somewhere. The one that recommends, not using synthetic gear lubes in diffs & transfer. With the exception of Mobil One gear lube. Any have there name or better yet can post a link here?

I just used Valvoline synthetic in my diffs. Hope they don’t blow up!

 

[saucebox]

I was searching for the differential shop mention in mud somewhere. The one that recommends, not using synthetic gear lubes in diffs & transfer. With the exception of Mobil One gear lube. Any have there name or better yet can post a link here?

Zuk @ gearinstalls.com? IDK if that's his rec, but he's the only shop that comes to mind.

 

[OwnerCS]

I just used Valvoline synthetic in my diffs. Hope they don’t blow up!

I previously used Mobil 1 and switched to the new Valvoline.

Due to the number of long hours off-roading and water crossings that I do (yes I have a vented system) I change fluids every 3 months. I spend an amount of time driving in 4Lo locked. each month and use the front eLocker. At the same interval, I could not see a color difference between Valvoline or the amount of graphite on the metal plug between it and Mobil 1. I realize this is not a normal use case. The new squeeze bottle just makes my frequent change routine much easier.

 

[OwnerCS]

I'm running a Harrop eLocker with LSD rear. I remembered this from the manual.

 

[OwnerCS]

Zuk @ gearinstalls.com? IDK if that's his rec, but he's the only shop that comes to mind.

I remember Zuk recommending changing the front diff fluid after 500 miles (break in) maybe the first round for break-in would be dino. I did use dino on that first 500-mile change after Zuk installed the Harrop.

 

[OffRoadRN]

So there's the front and rear diff plugs, how bad does that look? I did mine at the same time as my cousin, who has a 3rd gen 4runner. I read in the faq to use 80w-90, not 75w-99. The two shops in town didn't have enough 75w-90 for the both of us, so I used 80w-90. I think it was stp conventional. Would it be worth ordering synthetic in a year or something and doing this again? Does it matter that I used 80w-90? I still have to do the transfer case.

 

[OffRoadRN]

Duplicate

 

[AlpineAccess]

So there's the front and rear diff plugs, how bad does that look? I did mine at the same time as my cousin, who has a 3rd gen 4runner. I read in the faq to use 80w-90, not 75w-99. The two shops in town didn't have enough 75w-90 for the both of us, so I used 80w-90. I think it was stp conventional. Would it be worth ordering synthetic in a year or something and doing this again? Does it matter that I used 80w-90? I still have to do the transfer case.

View attachment 2842993

View attachment 2843006

How many miles are on this fluid?

 

[OffRoadRN]

How many miles are on this fluid?

No idea. The truck is new to me and has 245k on it. The Carfax showed oil changes every few thousand miles but that was it for maintenance records.

 

[AlpineAccess]

No idea. The truck is new to me and has 245k on it. The Carfax showed oil changes every few thousand miles but that was it for maintenance records.

Got it. That is a little more wear debris on the rear magnet than I see at normal service intervals (around 30k) but there are no "chunks" and it looks like the debris is very fine. The front looks normal to me, but every time I change front diffs on Toyotas (even a fulltime 4x4 like the 100) I am always surprised how clean the diff fluid is.

With no reference on the service life and change interval, that fluid could have been in there for a long time and who knows how many miles. Overall it looks like you're in good shape. Put some fluid back in and see how it looks in 30k.

 

[OffRoadRN]

Got it. That is a little more wear debris on the magnets than I see at normal service intervals (around 30k) but there are no "chunks" and it looks like the debris is very fine.

With no reference on the service life and change interval, that fluid could have been in there for over 100k. If that is the case, that amount of wear debris is quite good.

Alright, good to hear! Considering the history and the fact I didn't use synthetic oil, do you think it's worth changing out in a year or something, or just wait 30k miles?

 

[AlpineAccess]

Alright, good to hear! Considering the history and the fact I didn't use synthetic oil, do you think it's worth changing out in a year or something, or just wait 30k miles?

I wish I knew more about synthetic vs dino - there are some real experts out there that swear by certain fluids. What I can say is that having switched to synthetic in my 100, 1st Gen Tundra, Tacoma, and FJ Cruiser, I noticed no difference in performance or debris at changes but my wallet is lighter.

I did notice this year that I was hearing a light whine from my t-case on cold mornings (under 10*) and switched to synthetic in it. The whine was still there but seemed to go away a bit quicker with the synthetic. While the motor, trans, etc. all get to heat up as the vehicle idles in the driveway, the diffs and transfer case don't warm up as much so I just take it easy for a bit. It's probably just a function of having put quieter (newer) set of tires on it and actually hearing the whine.