Gear oil question

[SWTrail]

I'm gonna check the rear diff gear oil when I change my oil. All I can find at the auto store is 75-90 LS. Is it ok to use gear oil for limited slip doffs in this? It's a Trail with the locking rear diff. I'm guessing it's fine, but I wanted to double check.

Also, do you really need to change out the drain and fill plug washer/gaskets every time? Hate to have to put a new one on the fill plug every time you open it to check.

 

[bamma]

The LS is fine. I usually swap out the crush washer, but have done a few drain and fills where I reused it. Just make sure not to overtorque and watch for drips.

 

[ViperNL]

Used 75W90 Amsoil severe gear in mine everywhere, front, t-case, rear.

 

[SWTrail]

Ok thanks. I just checked it. Mostly clear with a grayish tint. Level was about 1/4" below the full opening with the diff cool to the touch. Should I top it off or is that ok? Reused the washer and torqued it to 30 ft lbs. I'm guessing it should be good to at least 15k.

 

[bamma]

Ok thanks. I just checked it. Mostly clear with a grayish tint. Level was about 1/4" below the full opening with the diff cool to the touch. Should I top it off or is that ok? Reused the washer and torqued it to 30 ft lbs. I'm guessing it should be good to at least 15k.

It should be filled till it starts dripping out.

I replaced mine at 10k miles, and it was dirty. Every 30k since. Seems there is some break in. Not a bad idea to replace, but I am conservative.

 

[SWTrail]

Yeah, I'll plan on changing it in a few days when I change the oil. Probably use Mobile 1 75w-90 LS. I wasn't planning on checking the front diff or transfer case until 15k or so. That sound reasonable?

 

[ViperNL]

I think Toyota recommends every 30k for severe duty. My diffs were pretty dark with that same hue at 40k. T-case looked pretty new at 40k. Also, t-case requires special 75w oil from Toyota at $50/qt or something. Needs 1.1 qt, I think. I just used the 75w90. Some people report losing an mpg. Mine went down a little (0.2mpg), then I disconnected the battery and gained an mpg, so I don't know.

 

[bamma]

Yeah, I'll plan on changing it in a few days when I change the oil. Probably use Mobile 1 75w-90 LS. I wasn't planning on checking the front diff or transfer case until 15k or so. That sound reasonable?

I replaced all 3 at just over 10k. Rear was the worst (gray), front diff was marginal, and transfer case still loked brand new in my limited w ft 4wd.

You will likely be fine at 30k, but I am glad I did it at 10k.

 

[SWTrail]

So I went ahead and changed the fluid. Used Toyota LT just to keep everything OEM for now. Took all 3L to get the oil to the fill hole opening. Old fluid was a bit dirty. Little sludge on the drain plug, but not too much. Probably could have gone 15k no problem or more.

I did notice that after changing it and then driving for 10-15 mins the rear axle was pretty warm to the touch. Almost more so that when I changed it. That normal. Wasn't too hot to touch. Just figured if anything it'd run cooler.

 

[1engineer]

So I went ahead and changed the fluid. Used Toyota LT just to keep everything OEM for now. Took all 3L to get the oil to the fill hole opening. Old fluid was a bit dirty. Little sludge on the drain plug, but not too much. Probably could have gone 15k no problem or more.

I did notice that after changing it and then driving for 10-15 mins the rear axle was pretty warm to the touch. Almost more so that when I changed it. That normal. Wasn't too hot to touch. Just figured if anything it'd run cooler.

The absolute only way to change (lower) operating temperatures of gearboxes is A) Adjust backlash differently or B) Change the viscosity of the fluid to fit your application better. I wouldn't do either unless you were the one who designed the gearbox.

 

[SWTrail]

I'm sure it's fine. I'm just gonna run with it.

 

[skag1T]

Changing transmission fluids early ?

Reviving this thread for a question re: transmission fluids:

I see a lot of people recommending changing all transmission fluids very early -- after the first $1k miles or so, to clean up the break-in metal particles, then do regular maintenance per the OEM maintenance schedule.

I don't mind the cost - what is everybody's opinion about this ?

I am sitting on 6qts of MOTUL Gear300 75W90 (and can get more if needed, I got a dealer close by). I also don't mind using the Toyota original oil.