ATF vs GL4 gear oil

[warthog]

I have a 2000 Nissan Patrol 4wd with a manual g/box and transfer case. The transfer case has a chain drive to the front drive shaft. Auto hubs on the front hubs.
It needs a less viscous, lighter oil. A heavier oil will cause the front output shift to turn even when in 2wd and the autohubs will engage which is not wanted.

Currently running Castrol transmax Z synthetic atf in it.

https://www.google.com/url?sa=t&sou...4QFnoECCkQAQ&usg=AOvVaw2SvOnL8LE1MZM7dAh6wv3s

Have recently put penrite pro gear 70w/75 synthetic gl4 gear oil in it.

https://penriteoil.com.au/products/pro-gear-70w-75-full-syn

Colour	Amber
Density at 15°C, kg/L	0.874
Viscosity, Kinematic, cSt at 40°C	38
Viscosity, Kinematic, cSt at 100°C	7.5
Viscosity Index	177
Zinc, Mass %	0.131
Viscosity, Brookfield at -55°C	109,680

They have the same viscosity at 40° and 100°c.

Will the 70w75 gear oil offer any wear advantage ?

 

[Kira]

I don't know but you'd sure think any gear oil would protect against wear better than any hydraulic (transmission) fluid.

A heavier oil will cause the front output shift to turn even when in 4wd and the autohubs will engage which is not wanted.

a) Have you experienced this effect yourself or are you simply mentioning a warning you know about?
b) Did you mean to type, "...even when in 2wd", instead of 4wd?

 

[Jetronic]

the front wheels tend to turn due to viscous drag but they don't transmit any power, you can easily stop them by hand when the car is running on a lift in 2wd

 

[warthog]

I don't know but you'd sure think any gear oil would protect against wear better than any hydraulic (transmission) fluid.
a) Have you experienced this effect yourself or are you simply mentioning a warning you know about?
b) Did you mean to type, "...even when in 2wd", instead of 4wd?

yes sorry 2wd.
yep ran 75w90 in there but it engaged one or both front hubs so that the diff was turning.
https://www.patrol4x4.com/threads/1-oil-for-diffs-and-gear-box-and-trasfer-isl-it-possible.379178/

Atf is specified by nissan when running autolocking hubs for this reason.

 

[nascarnation]

I got confused by the linked forum. Some guy used ATF in a Land Rover t-case and had bearing problems that didn't occur with gear oil? These issues always come back to what kind of failure are you trying to protect against. Most modern t-cases have chain drive and planetary gears (for the low range) and should work fine with ATF, especially the synthetic types. I was very surprised at the comments where the guy had Transmax turn black in a t-case in 60000 kms. Typically a t-case doesn't run as hot as the transmission and at that use, Transmax is just getting broken in, it's rated for 120,000 km by ZF for commercial applications.

 

[warthog]

I got confused by the linked forum. Some guy used ATF in a Land Rover t-case and had bearing problems that didn't occur with gear oil? These issues always come back to what kind of failure are you trying to protect against. Most modern t-cases have chain drive and planetary gears (for the low range) and should work fine with ATF, especially the synthetic types. I was very surprised at the comments where the guy had Transmax turn black in a t-case in 60000 kms. Typically a t-case doesn't run as hot as the transmission and at that use, Transmax is just getting broken in, it's rated for 120,000 km by ZF for commercial applications.

the transfer case fluid change interval is 40k km.
I have also left it in longer and yes, it does change colour .
I just dropped the transmax z yesterday after 30k km. A lot darker than it went in.
It is a forum, so yes you get some strange statements and theories but you get to know who knows their stuff pretty quickly.

Anyway I am no oil expert. My purpose in starting this thread was to hear if a synthetic gear oil of similar viscosity to synthetic atf will offer more protection. Perhaps not.

 

[nascarnation]

If you're wanting an ATF that might be better, try one that meets Allison TES-295 or the updated version TES-668. PAO based and hard to kill.

 

[warthog]

Asked the question about why the t/case is hammering the fluid on the patrol forum,

https://www.patrol4x4.com/threads/why-is-the-transfer-case-hard-on-fluid.419814/page-2#post-7162551

I have a lokka auto diff lock in the front diff. When 4wd is engaged the front diff is always locked. The car weighs 3000kg empty and has larger than STD mud terrain tyres on it.
The transfer case is under a lot of load and the ATF is struggling it appears.
Will see how the Pro gear 70w75 synthetic GL4 goes. If no good then the auto hubs will have to go and I'll put thicker gear oil in it.
More selective about when I put it in 4wd too.