Let's talk tranny/transfer case/diff fluids!

shovenose

Original poster
Member
Apr 24, 2016
318
SF Bay Area, CA
For my 02 envoy, I just want to make sure I use the right fluid for all these things.

For the transmission fluid, I'm thinking Valvoline Dex VI, for the differentials, Royal purple 75w-90 gear oil, but what about the transfer case?

And can I also use the same fluids for the 92 c1500 700r4 (obviously it has no transfer case so nevermind that) or should I use regular Dex3/Merc fluid since it's old?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Dex VI is backwards compatible to anything that uses Dexron fluids. And gear oil is gear oil so all good there but has to be synthetic for the TB but that's even better for the '92.

For the transfer case, as per the owners manual, it uses Auto-Trak II, takes about 2qt. Get yourself a fluid transfer pump for it.
Transfer case fluid change | GMTNation
 
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shovenose

Original poster
Member
Apr 24, 2016
318
SF Bay Area, CA
Unfortunately I am going to be taking them in for the fluid changes, but both are going to get new transmission pans with drain plugs, because I intend to do another fluid change next year when driving across the country. It'll be nice to use the same fluids in both, so Valvoline Dex VI and RYP 75w-90 it is!

As for the transfer case, O'Reilly carries Valvoline Transfer Case Fluid which is recommended for Auto-Trak II applications. Is that good?
 

Sparky

Member
Dec 4, 2011
12,927
No idea. Never tried it. Previously, there was no alternative, so I just used Auto Trak II from the dealer (about $10-12 a bottle I think). How much is the Valvoline fluid? If the cost is similar I'd be just getting the official stuff.
 

shovenose

Original poster
Member
Apr 24, 2016
318
SF Bay Area, CA
No idea. Never tried it. Previously, there was no alternative, so I just used Auto Trak II from the dealer (about $10-12 a bottle I think). How much is the Valvoline fluid? If the cost is similar I'd be just getting the official stuff.

It's retail on sale for like $8.something/qt, employee price on oil products isn't that good so probably like $7?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
<cringe> I'd stick with tried and true Auto-Trak II, which is also available in most parts stores.
 

Sparky

Member
Dec 4, 2011
12,927
That's the right stuff. 2 bottles of that.
 
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Sparky

Member
Dec 4, 2011
12,927
It really depends on the transfer case. It would not surprise me if the S10 uses the same fluid, but check the manual to be sure. Always the safest bet.

On the full size, up through the GMT800 Silverado/Sierra they used Auto Trak II fluid, but starting with the GMT900 Silverado/Sierra they switched to straight Dex VI ATF.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Just checked in GM-SI and S series used Dex III
 
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shovenose

Original poster
Member
Apr 24, 2016
318
SF Bay Area, CA
Little off topic but.... do you have to use that auto-trak fluid in all GM TC's
Such as my '03 s-dime
Actually for the 2002 envoy amsoils application website just showed ATF for transfer case fluid, idk what the difference is.
 

Sparky

Member
Dec 4, 2011
12,927
Which Envoy though? Remember, the Blazer/Jimmy each had a Trailblazer/Envoy package, before the GMT360 Trailblazer/Envoy.

If Amsoil is saying to put ATF in the 2002 GMT360 Envoy, they're flat out wrong.
 
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Sparky

Member
Dec 4, 2011
12,927
nah it said 4.2 i think

If that's the case, Amsoil is wrong. ATF is no bueno for the GMT360 transfer case. There was no difference in fluid requirements in any year of the GMT360 transfer cases. I had an 02 Trailblazer and the manual was very adamant about using Auto Trak II only.
 

shovenose

Original poster
Member
Apr 24, 2016
318
SF Bay Area, CA
Well, acdelco auto trak ii is on the way from Amazon, and my royal purple gear oil is here, so all is well :smile: thank you!
 

BrianF

Member
Jul 24, 2013
1,192
West central Sask.
I see now a few companies have a compatible AT2 fluid. Amsoil multi vehicle ATF and PetroCan Duradrive ATF. I am a firm believer in quality universal ATF`s now. I look at the transfer case, what is so special about it? It has a wet clutch pack. What is so special, rather unique about that? It needs a friction modified fluid. So does just about every auto trans out there. These systems have been around for many years and we do not have the confidence that the bit lube manufacturers do not know what they are doing?

I am just about due for another fluid change in my Tb. I have a quart of Amsoil multi ATF that will find its way into the transfer case and then I will use another similar fully synthetic multi vehicle ATF. They feature most of the same approvals and the viscosities are just about spot on.

If I am wrong I will die by the sword. I am past the premise that vehicle manufactures require unique, blended from unicorn type fluids. Many of these multi fluids are far superior to OEM.
 

JPutnam

Member
Jun 30, 2017
85
Ft. Bragg
I used Valvoline 75w90 in my axles and have no complaints. So much smoother. I was using RP and it just seemed too thick and felt like I was always pulling a trailer. Same with the Tahoe with M1, but the trailer had all 3 axles locked! When I changed it to the Valvoline it was a night and day difference and my mileage went from 13 to 15. Not bad for a 383 with 35's.
 

Sparky

Member
Dec 4, 2011
12,927
I see now a few companies have a compatible AT2 fluid. Amsoil multi vehicle ATF and PetroCan Duradrive ATF. I am a firm believer in quality universal ATF`s now. I look at the transfer case, what is so special about it? It has a wet clutch pack. What is so special, rather unique about that? It needs a friction modified fluid. So does just about every auto trans out there. These systems have been around for many years and we do not have the confidence that the bit lube manufacturers do not know what they are doing?

I am just about due for another fluid change in my Tb. I have a quart of Amsoil multi ATF that will find its way into the transfer case and then I will use another similar fully synthetic multi vehicle ATF. They feature most of the same approvals and the viscosities are just about spot on.

If I am wrong I will die by the sword. I am past the premise that vehicle manufactures require unique, blended from unicorn type fluids. Many of these multi fluids are far superior to OEM.

I just know people have toasted these transfer cases with regular ATF in the past.

Now Autotrak 2 compatible fluid is probably fine, but for what a buck or two difference I'm not one to bother trying it out.

My GMT900 pickup uses straight ATF in its transfer case so I have it easy now anyway!
 

JPutnam

Member
Jun 30, 2017
85
Ft. Bragg
I tried dex 6 in my Tahoe, which has the NP246, and it did not like it. The temps were fine and it turned fine, but it would not shift worth a crap.
 

BrianF

Member
Jul 24, 2013
1,192
West central Sask.
But yes to be fair and to be more precise. I trust brand name multi fluids that have the various approvals whether they be licensed or not. I
 

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