Changing Differential & Transfer Case Fluids - Pics Included

[JB.]

:iagree:

Which one to use 75W-140?
Mobil 1 Synthetic Gear Lubricant LS 75W-140
-VS-
75W-90?
Mobil 1 Synthetic Gear Lubricant LS 75W-90

I've considered using the heavier stuff a few times, mostly for the rear diff, but chickened out. For one thing, it would hit mpg noticeably, expecially if used in all 3. I don't think I'd use it in the transfer case but it's tempting to use it front and rear.

More discussion, recently, of some rear diff failures has got me thinking about it again.

 

[KB084RUNNER]

Amsoil makes a 75w110 which I may get for the rear diff next time. But the oil weight won't make any difference on a diff failure. Changeing the oil is what makes the difference.

 

[rdrunner]

the oil weight won't make any difference on a diff failure. Changeing the oil is what makes the difference.

That was my thinking. You can get Mobil 1 75/90 anywhere cheap and it's simple to do (though smelly). I'd rather just do it more often and know it's good.

 

[overlyunderme]

Subscribed.

 

[JB.]

But the oil weight won't make any difference on a diff failure. Changeing the oil is what makes the difference.

I was thinking in terms of cushioning the shock loads of aggressive, off-road ATRAC use.

 

[OrdnanceMarine]

I was thinking in terms of cushioning the shock loads of aggressive, off-road ATRAC use.

Looking at the spec the 75W-140 is on the very thinnest side of the 140 spec for cSt @ 100C, so in other words, it's just a hair thicker than a thick 90-weight oil, which is the next grade below 140. If the viscosity at 100C is the critical spec that Toyota needs the oil to meet then you're probably fine to try the 75W-140.

On the other hand the Mobil 1 75W-140 is SUBSTANTIALLY thicker at 40C than the 75W-90. So, if the driveline shock that you're concerned about is at temps closer to 40C then perhaps the 75W-140's propensity to be much thicker at cooler temps might actually mean that 75W-140 offers more cushioning in your real-world use but would run hotter since thicker oils don't allow heat to flow out of your gearbox as quickly since they "stick" more to the gears.

I don't know how hot a differential operates at. I can't imagine it's 100C but I really don't know. All I know is that according to these specs the 75W-90 is somewhat thinner at 100C and much thinner at 40C.

Without talking with a gear lubrication expert I wouldn't go the 70W-140 route.

Mobil 1 Synthetic Gear Lubricant LS
SAE Grade 75W-90
Viscosity (ASTM D445)
cSt @ 40ºC 99
cst @ 100ºC 15.2
Viscosity Index 142
Pour Point, ºC (ASTM D97) -39
Flash Point, ºC (ASTM D92) 150
[email protected] ºC g/ml (ASTM D4052) 0.859

Mobil 1 Synthetic Gear Lubricant LS
SAE Grade 75W-140
VViscosity (ASTM D445)
cSt @ 40ºC 170
cst @ 100ºC 24.4
Viscosity Index 175
Pour Point, ºC (ASTM D97) -48
Flash Point, ºC (ASTM D92) 207
[email protected] ºC g/ml (ASTM D4052) 0.872

 

[JB.]

.............I don't know how hot a differential operates at. I can't imagine it's 100C but I really don't know. All I know is that according to these specs the 75W-90 is somewhat thinner at 100C and much thinner at 40C.

Without talking with a gear lubrication expert I wouldn't go the 70W-140 route.

Interesting. I hadn't considered heat dissipation. Thanks for the cold water.

 

[MICA4R]

Looking at the spec the 75W-140 is on the very thinnest side of the 140 spec for cSt @ 100C, so in other words, it's just a hair thicker than a thick 90-weight oil, which is the next grade below 140. If the viscosity at 100C is the critical spec that Toyota needs the oil to meet then you're probably fine to try the 75W-140.

On the other hand the Mobil 1 75W-140 is SUBSTANTIALLY thicker at 40C than the 75W-90. So, if the driveline shock that you're concerned about is at temps closer to 40C then perhaps the 75W-140's propensity to be much thicker at cooler temps might actually mean that 75W-140 offers more cushioning in your real-world use but would run hotter since thicker oils don't allow heat to flow out of your gearbox as quickly since they "stick" more to the gears.

[email protected] ºC g/ml (ASTM D4052) 0.872

Thank you! This is really helpful. I'll stick with the lighter stuff and change it more often.

 

[MrBunnyRunner]

Just wanted to say thanks for all the PERFECT information and pictures! It's so nice to crawl under the truck and have the correct tools the first time. Almost takes the fun out of it.

 

[Zuke]

FYI I tried using a 24mm 12pt socket on the rear diff fill plug. The dam thing almost stripped the head. After reading a few other Toyota sites it is recommended to use a 15/16 6pt socket on that bolt. The 12pt socket wants to grab too much and with the head being so short it will easily strip it. The 15/16 is marginally smaller that the 24mm and the smaller size is better to prevent stripage.

 

[matthewy03]

This thread is still getting use. I just changed my rear and transfer case to Mobil 1 75w90. I couldn't get the drain plug off of the front and i felt like i was stripping it, so i stopped soaked it quite a few times with pb blaster but it will won't budge. I read in another thread about heating it up with a torch so i will give this a try when i can make it to the store to pick one of those up.

A couple things to keep in mind, if you use a pump, you will actually have to use more than what you think on the first one, because the pump will hold a fair amount of fluid ( at least mine did ).

When you take the transfer case drain plug out the fluid comes out like a rocket, i had my catch pan directly under the case, but when i removed it the fluid shot out a good foot and got all over the driveway, what a mess.

I am still learning mechanical things but i am happy to report that thanks to this thread and forum, I have accomplished yet another thing that I wouldn't have been able to do on my own, it was easy, and i saved quite a bit of money.

 

[Doctor Subie]

Snowbizx et al, thanks for this post! Great to have pics, tools, fluid capacities and torque specs all in one place.

Remember; 2 crush washers for each (minus oil drain pan of course...) -

Front Diff Drain
9043024003 (x2)

Rear Diff Drain
1215710010 (x2)

Transfercase Drain
9043018008 (x2)

Oil pan drain
9043012031 (x1)

One correction required; reverse the "Drain" an "fill" descriptions / colors on the transfer case they're backwards no biggie.

I don't post but this site is my bible and the members are GREAT! I sincerely appreciate everyone's input everyone helps each other; rare these days... Adios!

Just did the whole shebang while she was up on the lift--oil/filter, front/rear diff and transfercase.

On my front differential, the fill bolt and drain bolt took different washers--the drain bolt took 9043024003 (the big copper washer), but the fill bolt seems to be smaller, and quite similar to the transfercase washers? I just re-used the old one...

 

[message]

Did my front & rear diffs as well as transfer case this weekend. When I bought the 4runner last summer the dealer said they "changed all fluids". Interesting enough the transfer case fluid looked basically new as well as the rear diff. However the front diff came out black as ever. I'm assuming the front had never been changed.
With 127k now I should be good for a long time as I filled diffs and transfer case with Royal Purple 75W90. First drive out I definitely noticed a smoother ride and the cabin noise was quieter especially in the front.
Definitely agree that all crush washers should be replaced. Would hate to have to change one later on and lose $25 worth of fluid in the process. Cheap insurance indeed!
Below is a shot of the fluid from the front diff.

 

[jimithing]

Forgive me if I should know this but what hand pump are you guys using here?

 

[<<<<]

I used El-cheapo they had at Oriley's:

 

[morphius909]

Bit of a dumb question....

but I have a stock 07 Sport....

How do you put the Vehicle on Stands? Do you simply Raise the front and put it on stands, then raise the back and put the back on stands???

Seems a bit dangerous...am I missing something here in regards to the logistcs of putting the vehicle on stands so I can change the Diff fluids?

 

[JB.]

...am I missing something here in regards to the logistcs of putting the vehicle on stands so I can change the Diff fluids?

Not that I know of, except you may not need stands. I only use stands for lubing so I can turn the shafts, otherwise ramps or even nothing for the diffs. Since I'm nearly always going to lube if I'm under there, though, and I like as much space as I can get, it's almost always stands.

1. Wheel chocks at the rear.
2. Floor jack under the bump on the front skid. Go higher than it seems you need to. Front end will lower considerably when you jack up the rear.
3. Position two stands under frame somewhere in the vicinity of where the tubular cross brace connects to outer portion of frame.
4. Floor jack under rear pumpkin then position two jack stands.

I use 6 stands total. Two are positioned removably as safety backups under whichever end I'm working. If someone has a better system, I'd love to hear it.

 

[pattycakes]

FWIW I have been changing toyota diffs for 25 years and have never used a new crush washer on the drain or fill and have never had a leak , I could bet a lot that even the dealer mechanics don't use new washers either as I've never seen them do it , come to think of it I have never used a torque wrench either , ya just get a feel for it after a while . I suggest using one though ya can't go wrong if ya do. I may even start also , getting old ya lose the feel of alot of things. :moon: , I am pretty anal and change mine every 20 thousand KM , just because they are so easy to do with the drain plug , no cover plates and silicone to deal with. I may extend that a bit now as I started using synthetic in the last couple of years . It is important to change more frequent if you live in a cold climate area no mater what the milage is on the oil , as the temperature change in the diff creates condensation inside and that water will rust and pitt bearings etc... Trust me I,ve pulled a lot of toyota diffs apart.I also replace my fill plugs with drain plugs so there are two magnets in there . Another tip is once drained I reinstall the drain plug hand tight and pour a half a liter of fluid in and then take out the drain plug again , this is to flush / remove the approx 300ml of oil that doesnt come out that is sitting in the bottom of the diff . Yes I am anal.

 

[message]

I put the front on stands to get some slant so more of the fluid would come out of the front diff and transfer case. I also jacked up the drivers side rear so more fluid would come out of the rear diff. Then I put it up on 4 jack stands, leveled it and filled all 3 with fluid.

 

[ozzyleven]

matthewy03, were you using a six-point socket when you thought you were stripping the plug? When I did my front, I was using one of those 12-point or whatever they are sockets and it felt like it was stripping. Went and bought a six-point one and it came right out.