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92 C1500 and 02 Envoy ATF/TC/Diffs #4458300
07/13/17 02:01 PM
07/13/17 02:01 PM
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
dogememe Offline OP
dogememe  Offline OP
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
For the 4WD GMC Envoy, I picked up some ACDelco Auto Trak II for the transfer case, but I'm not sure about the front/rear differentials. I picked up Royal Purple 75W-90 for $13/qt, but before I put that in, is that the best choice? I can always return the Royal Purple... As for the 4L60E, O'Reilly carries Valvoline Dex VI, or I can get ACDelco Dex VI on Amazon for $5.91/qt. What about Royal Purple Max ATF? I feel like that should be a more premium product, but it specifically states it doesn't meet Dex VI specs...

For the 2WD Chevy truck, for the differential, should I use the same Royal Purple 75W-90, and the same ACDelco Dex VI ATF for the 700R4, or are there better options?
Thanks for any input.


2007 Crown Vic P71 4.6 ~126K Miles, Royal Purple HPS 5W-30, Royal Purple Filter, Daily Driver, 5K OCIs.
2010 Escape FWD 2.5 ~84K Miles, Castrol Edge EP 5W-30, Wix Filter, Rented on Turo, 10-15K OCIs.
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4458397
07/13/17 03:40 PM
07/13/17 03:40 PM
Joined: Feb 2013
Posts: 10,686
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline
Joined: Feb 2013
Posts: 10,686
Phoenix, AZ
I had a 96' C1500 and used Mobil 1 75w90 for the rear end, worked great. Limited slip additive built in.

My grandparent's have an 02' Trailblazer (same as Envoy) and last year I changed the rear end oil with Valvoline SynPower 75w90, it too has the Limited Slip additive. Works great.


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: Nick1994] #4459210
07/14/17 12:02 PM
07/14/17 12:02 PM
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
dogememe Offline OP
dogememe  Offline OP
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
Originally Posted By: Nick1994
I had a 96' C1500 and used Mobil 1 75w90 for the rear end, worked great. Limited slip additive built in.

My grandparent's have an 02' Trailblazer (same as Envoy) and last year I changed the rear end oil with Valvoline SynPower 75w90, it too has the Limited Slip additive. Works great.


Hmm, I was under the impression that no additives are required for G80s on GM trucks and SUVs? I'll think about the Mobil, It's actually a bit cheaper, $10/qt on Amazon vs $13/qt for the Royal Purple. Either way I gotta do something, something is howling on the Envoy above 65mph, I think it's the rear diff

Last edited by dogememe; 07/14/17 12:07 PM.

2007 Crown Vic P71 4.6 ~126K Miles, Royal Purple HPS 5W-30, Royal Purple Filter, Daily Driver, 5K OCIs.
2010 Escape FWD 2.5 ~84K Miles, Castrol Edge EP 5W-30, Wix Filter, Rented on Turo, 10-15K OCIs.
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4459346
07/14/17 02:24 PM
07/14/17 02:24 PM
Joined: Aug 2013
Posts: 2,529
Central Maryland
HangFire Offline
HangFire  Offline
Joined: Aug 2013
Posts: 2,529
Central Maryland
Originally Posted By: dogememe
Either way I gotta do something, something is howling on the Envoy above 65mph, I think it's the rear diff


Could be the diff input bearing, where the driveshaft comes in. My indy mechanic said he replaced a BUNCH of them on GM's in that model year range (early 2000's), and some other brands. My Dakota rear was howling, had it replaced. I still have it... a Timkin, looked fine until you spun it enough to see some of the roller bearings were all torn up on one side. Random ones, not all of them, all about 1/4 to 1/3 of the way around. Seems to have been a metallurgy problem.

Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4459373
07/14/17 02:55 PM
07/14/17 02:55 PM
Joined: Feb 2013
Posts: 10,686
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline
Joined: Feb 2013
Posts: 10,686
Phoenix, AZ
Originally Posted By: dogememe
Originally Posted By: Nick1994
I had a 96' C1500 and used Mobil 1 75w90 for the rear end, worked great. Limited slip additive built in.

My grandparent's have an 02' Trailblazer (same as Envoy) and last year I changed the rear end oil with Valvoline SynPower 75w90, it too has the Limited Slip additive. Works great.


Hmm, I was under the impression that no additives are required for G80s on GM trucks and SUVs? I'll think about the Mobil, It's actually a bit cheaper, $10/qt on Amazon vs $13/qt for the Royal Purple. Either way I gotta do something, something is howling on the Envoy above 65mph, I think it's the rear diff
It's already included in the fluid and doesn't hurt open diffs.


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4459646
07/14/17 08:44 PM
07/14/17 08:44 PM
Joined: Sep 2015
Posts: 2,259
Malaysia
zeng Offline
zeng  Offline
Joined: Sep 2015
Posts: 2,259
Malaysia
Originally Posted By: dogememe
Either way I gotta do something, something is howling on the Envoy above 65mph, I think it's the rear diff

Had you been consistently using 75W90 of low-ish [email protected]*C of ~100, giving rise to howling ?

Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: zeng] #4464088
07/19/17 03:14 PM
07/19/17 03:14 PM
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
dogememe Offline OP
dogememe  Offline OP
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
Originally Posted By: zeng
Originally Posted By: dogememe
Either way I gotta do something, something is howling on the Envoy above 65mph, I think it's the rear diff

Had you been consistently using 75W90 of low-ish [email protected]*C of ~100, giving rise to howling ?


To be honest it's hard to tell where the noise is coming from, now I'm actually leaning towards a wheel bearing, since Trailblazer/Envoys seem to go through bearing/hub assemblies frequently. The fluid is still overdue for changing so that's all still gonna happen sooner than later.

Last edited by dogememe; 07/19/17 03:14 PM.

2007 Crown Vic P71 4.6 ~126K Miles, Royal Purple HPS 5W-30, Royal Purple Filter, Daily Driver, 5K OCIs.
2010 Escape FWD 2.5 ~84K Miles, Castrol Edge EP 5W-30, Wix Filter, Rented on Turo, 10-15K OCIs.
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4464500
07/20/17 12:36 AM
07/20/17 12:36 AM
Joined: Feb 2015
Posts: 702
Sask, Canada
BrianF Offline
BrianF  Offline
Joined: Feb 2015
Posts: 702
Sask, Canada
I used Auto Trak II in mine. 7$ a liter at the local dealer. The diffs got 75w90 Amsoil. Nothing special. I don't think this stuff has the friction modifiers in it..... either way that was over 5 years ago and its running fine.

As for the howling, see if it is the front unit bearings. Both fronts went bad around 160,000km on mine. I tried to isolate which bearing by steering in either direction to load the outside bearing. Never could determine a difference in sound. Replaced both, which both were bad.


2006 Trailblazer LT. Castrol Edge with Fram Ultra.
2017 Ram 3500 SLT Megacab. Duron SHP 10w30 with Hastings LF608.
1993 GMC 1500. It has oil and still runs
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4464501
07/20/17 12:43 AM
07/20/17 12:43 AM
Joined: Feb 2015
Posts: 702
Sask, Canada
BrianF Offline
BrianF  Offline
Joined: Feb 2015
Posts: 702
Sask, Canada
On a further note: The front bearings had no play, no vibration when spun by hand or at highway speed. Just the audible howl at speed. When removed they were both found to have excessive resistance when spun compared to fresh bearings.


2006 Trailblazer LT. Castrol Edge with Fram Ultra.
2017 Ram 3500 SLT Megacab. Duron SHP 10w30 with Hastings LF608.
1993 GMC 1500. It has oil and still runs
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4464574
07/20/17 06:10 AM
07/20/17 06:10 AM
Joined: Oct 2008
Posts: 4,100
Kuwait
Falcon_LS Offline
Falcon_LS  Offline
Joined: Oct 2008
Posts: 4,100
Kuwait
75W-90 will do well in both differentials. You can still use Dexron III (H) in the transmission, even though it is not being licensed a lot of them do meet the spec. Or you can run Amsoil ATF.


99 Explorer: H17W02/GC 0W40
00 Pajero: XG9688/MC 15W40
01 Grand Marquis: XG2/XCess 5W40
03 Expedition SSV: XG2/XCess 5W40
05 Envoy: XG9837/5W30 ESP
06 XJ8L: C2C41611/5W30 ESP
07 SRX: XG8765/5W30 ESP
Re: 92 C1500 and 02 Envoy ATF/TC/Diffs [Re: dogememe] #4469987
07/25/17 12:47 PM
07/25/17 12:47 PM
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
dogememe Offline OP
dogememe  Offline OP
Joined: Apr 2017
Posts: 929
SF BAY AREA, CA
Thanks all, got the Envoy sorted, I had the Auto Trak II put in the transfer case, and the 75w-90 put in the diffs, apparently my front diff was completely empty before, oops, lol. Now to see if MPG is any better. I will inspect wheel bearings for play when doing shocks if I end up doing that myself, and if the shop does it I'll ask them to make sure there is no play, I did notice some weird wear on one of the old tires, and I don't wanna mess up my new tires, so gotta see what's up with that. Still have to do tranny fluid and service the C1500, but I'm trying to space things out a bit financially.

Last edited by dogememe; 07/25/17 12:54 PM.

2007 Crown Vic P71 4.6 ~126K Miles, Royal Purple HPS 5W-30, Royal Purple Filter, Daily Driver, 5K OCIs.
2010 Escape FWD 2.5 ~84K Miles, Castrol Edge EP 5W-30, Wix Filter, Rented on Turo, 10-15K OCIs.

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