Gear oils and yellow metals

[DrRoughneck]

My Toyota Tacoma's transfer case contains bronze parts and bronze is a copper alloy.

The OEM recommends 75W90 gear oil in the trnasfer case but I have read repeatedly on BITOG that some such gear oils can corrode/disolve yellow metals.

The oil I am considering is Mobil Delvac 1 Synthetic 75W90. Is this oil OK with yellow metals?

 

[Michael_P]

Amsoil or Redline MTF are proven to do well with yellow metals. You can get them in 75W90 GL-4

 

[SavagePatch]

From what I've read no. I ended up using Redline MT90 in both the transmission and transfer case of my 98 Tacoma 3.4L just incase there was some bleed through between the two of them. The Mobil will be fine in your front and rear differentials though.

 

[CT8]

Originally Posted By: DrRoughneck
The OEM recommends 75W90 gear oil in the trnasfer case but I have read repeatedly on BITOG that some such gear oils can corrode/disolve yellow metals.
It makes you wonder ?Those stupid manufactures recommending a questionable oil. Try as mentioned Redline MT90 or a similar oil. We read stuff but most GL5 lubes have metal deactivators to control or protect yellow metals and all yellow metals aren't the same.

 

[expat]

Originally Posted By: DrRoughneck
My Toyota Tacoma's transfer case contains bronze parts and bronze is a copper alloy.

The OEM recommends 75W90 gear oil in the trnasfer case but I have read repeatedly on BITOG that some such gear oils can corrode/disolve yellow metals.

The oil I am considering is Mobil Delvac 1 Synthetic 75W90. Is this oil OK with yellow metals?


I think you need to look beyond the 75w-90 viscosity rating and look at the GL rating required.
Most gear oils available are rated GL5, I would guess your transfer case will require a GL4 lube because of the yellow metal used.

As mentioned, some MTL's (manual transmission lubes) are rated yellow metal compatable,
and should be fine for your application.

 

[simple_gifts]

Quote:


I think you need to look beyond the 75w-90 viscosity rating and look at the GL rating required.


+1; no guessing or uncertainty is involved here.

 

[DrRoughneck]

Right, actually they call for GL4 in the transfer case so redline MT90 then.

 

[Kamele0N]

You are looking for.....

75W90 GL4 (original)

or 75W90 GL4+

Or 75W90 GL4/5

Or 75W90 GL5/MT-1

Last three oils have protection of GL5 spec.....BUT are yellow metal friendly!

 

[HMan]

If something says it is good for limited slip differentials, do not put it in. I made that mistake with some 75W90 GL5/MT-1 oil and it made my syncros near useless. MTG made my syncros work okayish, but there is occasionally a grind going into 3rd.

 

[zeng]

Originally Posted By: DrRoughneck
Right, actually they call for GL4 in the transfer case so redline MT90 then.




Dumb question here, does tacoma tcase have brass synchro ?

 

[DrRoughneck]

Originally Posted By: Kamele0N
You are looking for.....

75W90 GL4 (original)

or 75W90 GL4+

Or 75W90 GL4/5

Or 75W90 GL5/MT-1

Last three oils have protection of GL5 spec.....BUT are yellow metal friendly!


Interesting. I have Mobil Delvac 1 75W90 rated GL5/MT-1 but from according to previous posts it should not be used in transfer cases with bronze parts. You're saying it iss yellow-metal friendly thus OK.

Can anyone confirm?

 

[DrRoughneck]

Originally Posted By: zeng
Originally Posted By: DrRoughneck
Right, actually they call for GL4 in the transfer case so redline MT90 then.




Dumb question here, does tacoma tcase have brass synchro ?


I'm basing my assumption that it does have bronze parts based on this video of a Tundra transfer case function: https://www.youtube.com/watch?v=4UoBCIjWIoU

I assume the Tacoma is similar enough to work the same and have bronze parts too.

 

[zeng]

Originally Posted By: DrRoughneck
Originally Posted By: Kamele0N
You are looking for.....
75W90 GL4 (original)
or 75W90 GL4+
Or 75W90 GL4/5
Or 75W90 GL5/MT-1
Last three oils have protection of GL5 spec.....BUT are yellow metal friendly!

Interesting. I have Mobil Delvac 1 75W90 rated GL5/MT-1 but from according to previous posts it should not be used in transfer cases with bronze parts. You're saying it iss yellow-metal friendly thus OK.Can anyone confirm?



KameleON is right, that any GL5's of today are yellow metal friendly.Gone were the days....
All 3 recommended gear oils of his, in relation to a typical GL4, offer stronger components wear protection ..... through stronger EP/AW additive package, and possibly higher operating viscosity.


Originally Posted By: DrRoughneck
Originally Posted By: zeng
Dumb question here, does tacoma tcase have brass synchro?

I'm basing my assumption that it does have bronze parts based on this video of a Tundra transfer case function: https://www.youtube.com/watch?v=4UoBCIjWIoU
I assume the Tacoma is similar enough to work the same and have bronze parts too.



With bronze synchro, KameleON's GL4+ or GL4/GL5 may be a good option.
Delvac 1 GL5 may be lacking an appropriate FM for synchro.

 

[DrRoughneck]

Thanks.
Please take a look at that video at 10:46 at the moment the output shaft is connected to the drive gear of the chain in the transfer case:
https://www.youtube.com/watch?v=4UoBCIjWIoU

Typically switch from 2WD to 4WD occures on straight road when front and rear axles are spinning at nearly matching speed. In that case do you think the lack of FM would be detrimental?

 

[zeng]

I find the question tough to answer.

Let other experts chime in ...

 

[MinamiKotaro]

I've been using GL5, 75w90 in my Bug transaxle for years. Works great, the synchros haven't melted.

I was using it in the old van's transmission, too, before I went to synchromesh fluid. No issues there, either.

 

[expat]

GL5 in my Triumph's diff made the oil turn green and the thrust washers disappear:-(

 

[Olas]

MT90, MT85 and MTL are all contenders, depending how hard you work the vehicle

 

[MolaKule]

Originally Posted By: DrRoughneck
My Toyota Tacoma's transfer case contains bronze parts and bronze is a copper alloy.

The OEM recommends 75W90 gear oil in the trnasfer case but I have read repeatedly on BITOG that some such gear oils can corrode/disolve yellow metals.

The oil I am considering is Mobil Delvac 1 Synthetic 75W90. Is this oil OK with yellow metals?


The question is: what is the correct friction modification and what is the correct viscosity to use?

Dedicated MTL's of the correct viscosity, such as Redline's MT-90 and Amsoil's MTG, have friction modifiers and viscosity closer to what is needed in a Toyota's Transfer Case for all-weather use.

This specific recommendation DOES NOT APPLY to those Transfer Cases that specify Dexron III, or AutoTrac fluids.