Transfer case vs Diff - Which runs hotter?

[DV0993]

Hi all,

I found some Amsoil Severe Gear 75w110 hiding in the back of my garage - I also have some 75w140.

I'm doing a diff and transfer case fluid change on my RX330 in the coming months and was thinking of putting the 75w140 in the transfer case on the basis that it may be the "hotter" component since its crammed in close to the engine/gearbox/exhaust etc.

75w110 in the diff.

Does this make sense? Any thoughts?
Thanks

 

[rumcapital23]

how many miles on the 75W110 in the transfer case at the moment?

 

[DV0993]

30,000 miles of Amsoil Severe Gear 75w90

 

[burbguy82]

I am not sure of your TCASE.......and how it is lubricated.......by pump or sling. Pumps would not like the 140 in my opinion.

Not knowing that above info, I would put the lighter stuff in the TCASE and the heavier stuff in the read end.

 

[brandon9715]

Lots of transfer cases spec ATF, so I would check yours before putting gear oil in it. I run Amsoil ATL in my transfer case and severe gear in my differentials.

 

[ka9mnx]

I would guess the diff runs hotter.

 

[SC Maintenance]

Transfer case isn't under load much, so likely doesn't generate the heat a rear diff would. As mentioned, most spec ATF.

 

[Jetronic]

I would guess the diff runs hotter.

yes, it transfers the same amount of power + has to deal with different wheel speeds.

That said, I always used diff oil (gl-5) in both when servicing them, and MTF for the gearbox if it was a manual.

 

[joegreen]

I don’t know how that transfer case works but the differential is going to have gears sliding on each other which definitely heats the fluid.

 

[D60]

Diff runs hotter.

The ATF t-cases I've been in just run an eccentric pump. It *would* theoretically pump gear oil, but probably not a lot when cold.

I drained an NP231J where someone had unknowingly filled with gear oil. Didn't seem to hurt it, but I never had need to open it up.

In OBS Fords the BW1356 was VERY common Bronco thru F350, gasser thru PSD. It would regularly destroy its pump arm and then the pump would just free-spin and pump nothing. Even these seemed to last a LONG time after this would happen, leading me to believe there's enough splash lube to keep it alive for the most part. These were ATF.

I honestly don't know what pump Toy uses in their 'cases that spec gear oil -- never been into one

 

[Highboy]

I believe Toyota specs 80-90 for this application. I know my Highlander does.
A 75w-90 would be the thickest I would use.

 

[Snagglefoot]

I checked the Amsoil site. I couldn’t find the RX330 but found the RX350. It specified 75W85 Synthetic which is a lighter weight in the grand scheme of things. No ATF for this transfer case.

 

[edyvw]

Hi all,

I found some Amsoil Severe Gear 75w110 hiding in the back of my garage - I also have some 75w140.

I'm doing a diff and transfer case fluid change on my RX330 in the coming months and was thinking of putting the 75w140 in the transfer case on the basis that it may be the "hotter" component since its crammed in close to the engine/gearbox/exhaust etc.

75w110 in the diff.

Does this make sense? Any thoughts?
Thanks

No. Run in all 75W90.

 

[DV0993]

Thanks all - I'll put 75w110 in the transfer case (which as I understand it, is the old "thicker" 75w90).

Is there any harm to going thicker?

 

[JRay’07]

Thanks all - I'll put 75w110 in the transfer case (which as I understand it, is the old "thicker" 75w90).

Is there any harm to going thicker?

 

[edyvw]

Thanks all - I'll put 75w110 in the transfer case (which as I understand it, is the old "thicker" 75w90).

Is there any harm to going thicker?

On the other hand, I don't understand this part!
How is 75W110 as thick as 75W90? Grades as far as I know, did not change.

 

[ka9mnx]

About 20 years ago API reduced the 90 grade in 75w-90 to increase fuel economy and left a gap between 90 and 140. I think Amsoil and Red Line were the first to introduce 75w-110 to fill the gap.

 

[Pablo]

On the other hand, I don't understand this part!
How is 75W110 as thick as 75W90? Grades as far as I know, did not change.

Yep they (SAE) halved the old 90 range to "new" 90 and the new 110. In J306

OLD:

NEW:

 

[edyvw]

Yep they (SAE) halved the old 90 range to "new" 90 and the new 110. In J306

OLD:
View attachment 252351


NEW:


View attachment 252349

Yes, thanx for reminder. I remember now the 110 thing.
But, minimum still stayed the same. Not sure in RX330 would make any difference.
On track I know bunch of people who are pushing a lot of power go 110 if it calls 90. Not sure that is necessary here.

 

[ka9mnx]

Some OEM diffs needed the higher KV that SAE reduced.