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#1305696 - 12/08/08 09:05 PM Silverado 4x4 Differential Fluid Intervals
zulu Offline


Registered: 01/21/08
Posts: 528
Loc: Kansas
I have an 06 Silverado 5.3 4x4 with about 35k on it. The manual indicates severe service intervals on the transmission and transfer case are 50k. It doesn't make a mention what the front/rear diffs intervals are. Should I do them at 50k too, or earlier? It doesn't tow hardly at all, but it does see lots of in-town short trip driving.

Also, the rear it specd for 75W-90 syn, but the front is plain 80W-90. Can I use syn in both, or should I stick to the plain jane stuff up front?


Edited by zulu (12/08/08 09:07 PM)
_________________________
09 Silverado 5.3 -> M1 5W-30/AC Delco PF48
12 Civic Si 2.4 -> Honda (CP Blend) 0W-20/Honda A02

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#1305858 - 12/09/08 12:20 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: zulu]
Bill in Utah Offline



Registered: 11/11/02
Posts: 12781
Loc: UT
You can (and should) replace the fluid in the diffs around 45-50k.

Your 2006 can use syn in the front since they fixed the problem with the vent in 2004.

I changed mine every 45k on both my Silverado and my Moms Silverado. Used 75w-90 in the front (conventional since mine was a 2000 and hers is a 2002) and Syn 75-90 in the rear. I'd suggest Amsoil as they make REAL good fluids.

After that change you'd be good to go for 100k more miles.

Take care, bill

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#1305969 - 12/09/08 05:09 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: Bill in Utah]
NHHEMI Offline


Registered: 07/06/07
Posts: 5112
Loc: NH
I always change my diff fluids for the 1st time somewhere between 5K-10K max. The inital run of gear oil gets pretty cruddy and full of metal as the gears break in. If they have never been changed in your truck then change them now. After that my personal opinion is once a year/15K for conventional gear oil or every other year/30K for synthetics. That is for daily drivers as well. If you off road, tow a lot, plow, etc... then I reccomend only synthetic and a once a year change. It is cheap insurance that you never have a failure.

I had a 2005 Silverado and a 2007(NBS) Silverado. Both also spec'd 75W-90 synthetic for the rear and 80W-90 for the front. I ran 75W-90 synthetic in both. The 75W-90 is a superior product to the 80W-90 so use it with confidence. I used Royal Purple MaxGear. You will need 5 bottles to do the job and have a little left in one of them at the end. It is excellent gear oil and did really well in both trucks. I run RP MG in my Dodges as well and it performs as well there too.

Note - don't waste your money on the GM fluids if you were thinking about it. The prices are ridiculous and the products average. The 80W-90 will set you back about $14 p/bottle and the 75W-90 Synthetic $25+ p/bottle at the dealer. CRAZY! You can get RP MG, or any of the other aftermarket full synthetics, for under $15-$16 a bottle( I pay just $9-$11 for the RP - so shop around for best pricing )and have a better product.


Edited by NHHEMI (12/09/08 05:10 AM)
_________________________
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2014 Jeep Cherokee
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#1306667 - 12/09/08 05:21 PM Re: Silverado 4x4 Differential Fluid Intervals [Re: NHHEMI]
artificialist Offline


Registered: 09/23/07
Posts: 6543
Loc: Florida
Buy 75w90 syn for both, or if you are really worried about specs, buy Amsoil 80w90 for the front and some syn 75w90 for the back.

Nearly all auto parts stores have 75w90 syn in stock, so don't worry about availability. Dealer GL-5 gear oil is not some unique exotic fluid that is specially matched to your truck.
_________________________
2010 Lancer Ralliart Sportback

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#1307158 - 12/10/08 05:25 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: artificialist]
NHHEMI Offline


Registered: 07/06/07
Posts: 5112
Loc: NH
 Originally Posted By: artificialist
Dealer GL-5 gear oil is not some unique exotic fluid that is specially matched to your truck.


Yeah, but it has that really nice grape smell that makes it worth $25-$30 a bottle...
_________________________
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2014 Jeep Cherokee
"Latitude"
3.2L V6 4WD( ADI )


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#1308046 - 12/10/08 08:29 PM Re: Silverado 4x4 Differential Fluid Intervals [Re: zulu]
zulu Offline


Registered: 01/21/08
Posts: 528
Loc: Kansas
Did it today. Thanks for everybody that replied. I used Mobil 1 75W-90 in both front/rear because it was the easiest to get around here, and had the best reviews outside of Amsoil SVG. The front was a piece of cake, but the rear sucked. I have an aftermarket catback with dual tips, and the left pipe runs right in front of the rear diff cover. It took some weird angles and perfect size wrenches to get to the bolts, and then took some time to carefully get the cover off. Fluid wasn't horible, but definately black. Dark film all over the ring/pinion/locker, and a bit of goop/sludge caked on the magnet. Glad I went ahead and did this. Going to run a short interval to try and clean up any residiual deposits inside.
_________________________
09 Silverado 5.3 -> M1 5W-30/AC Delco PF48
12 Civic Si 2.4 -> Honda (CP Blend) 0W-20/Honda A02

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#1308333 - 12/11/08 06:19 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: zulu]
Johnny Offline


Registered: 05/27/02
Posts: 14013
Loc: Retired | Wausau, WI
The Mobil 1 75W-90 will serve you well. There is really no need to run a short interval. Just change it again in another 50-60K.

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#1332480 - 01/06/09 11:05 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: Johnny]
FrankN4 Offline


Registered: 04/18/08
Posts: 1093
Loc: Kentucky
I have a 2008 Silverado that I am getting ready to change the rear axle gear oil. I just today called Mobil 1 about their 75W-90 synthetic and they said it did not meet GM specks. I called Valvoline and they said their 75W-90 synthetic did not meet GM specks, I have not called Amsoil yet but will later today.

If two oil companies say their product does not meet a spec and both recommend using the GM gear oil, I think I am going to do that.
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#1332599 - 01/06/09 01:28 PM Re: Silverado 4x4 Differential Fluid Intervals [Re: FrankN4]
Jim Allen Offline


Registered: 08/12/05
Posts: 4477
Loc: NW Ohio
 Originally Posted By: FrankN4
I have a 2008 Silverado that I am getting ready to change the rear axle gear oil. I just today called Mobil 1 about their 75W-90 synthetic and they said it did not meet GM specks. I called Valvoline and they said their 75W-90 synthetic did not meet GM specks, I have not called Amsoil yet but will later today.

If two oil companies say their product does not meet a spec and both recommend using the GM gear oil, I think I am going to do that.


What spec? Is there something new or improved about the '08 that requires some special oil? Just an AAM axle, very much like what's been built for decades and the "official" GM stuff doesn't have a great rep.

I honestly don't understand why someone at either of those companies would tell you what they did but wonder if they offered some specifics?
_________________________
Jim Allen
Keepin' the Good Old Days of Four Wheeling Alive

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#1332777 - 01/06/09 03:37 PM Re: Silverado 4x4 Differential Fluid Intervals [Re: Jim Allen]
Jim 5 Offline


Registered: 05/25/05
Posts: 4008
Loc: Calgary Canada
There is a GM TSB that over-rules the 80w-90 spec for the front axle for cold climates. It is my understanding that all GM's spec 75w-90 for the front diffs in Canada. They wouldn't bother with a TSB like this for no reason. If I lived anywhere that got any cold weather whatsoever, I'd be using a 75w-90 synth in the front and rear diffs (which I do).
_________________________
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07.5 GMC Sierra 2500HD LMM Rotella 15w-40
09 Odyssey EX-L CT 5w-20
66 Bronco QS 10w-30
08 BMW K1200S Rt 15w-40
08 Pitster Pro X4 Rt 15w-40

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#1332839 - 01/06/09 04:15 PM Re: Silverado 4x4 Differential Fluid Intervals [Re: Jim Allen]
FrankN4 Offline


Registered: 04/18/08
Posts: 1093
Loc: Kentucky
 Originally Posted By: Jim Allen
 Originally Posted By: FrankN4
I have a 2008 Silverado that I am getting ready to change the rear axle gear oil. I just today called Mobil 1 about their 75W-90 synthetic and they said it did not meet GM specks. I called Valvoline and they said their 75W-90 synthetic did not meet GM specks, I have not called Amsoil yet but will later today.

If two oil companies say their product does not meet a spec and both recommend using the GM gear oil, I think I am going to do that.


What spec? Is there something new or improved about the '08 that requires some special oil? Just an AAM axle, very much like what's been built for decades and the "official" GM stuff doesn't have a great rep.

I honestly don't understand why someone at either of those companies would tell you what they did but wonder if they offered some specifics?


The owners manual says to use "SAE 15W-90 Synthetic Axle Lubricant (GM part Number US 89021677 Meeting GM Specification 9986115)

I called Mobil and asked them if they met that specification with their synthetic 75W-90. They put me on hold for a very short time, came back and said their synthetic gear lube did not meet GM specification and they did not recommend its use. When I called Valvoline, before I could even finish the spec number they said that was a GM specification and none or their gear lubes would meet that specification, I would have to get that one from the dealer. Neither would talk about specifics, I did ask. Honestly, I don't blame them for saying nothing.
_________________________
Actually, I never was as good as I used to be.

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#1333487 - 01/07/09 05:41 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: FrankN4]
NHHEMI Offline


Registered: 07/06/07
Posts: 5112
Loc: NH
 Originally Posted By: FrankN4
 Originally Posted By: Jim Allen
 Originally Posted By: FrankN4
I have a 2008 Silverado that I am getting ready to change the rear axle gear oil. I just today called Mobil 1 about their 75W-90 synthetic and they said it did not meet GM specks. I called Valvoline and they said their 75W-90 synthetic did not meet GM specks, I have not called Amsoil yet but will later today.

If two oil companies say their product does not meet a spec and both recommend using the GM gear oil, I think I am going to do that.


What spec? Is there something new or improved about the '08 that requires some special oil? Just an AAM axle, very much like what's been built for decades and the "official" GM stuff doesn't have a great rep.

I honestly don't understand why someone at either of those companies would tell you what they did but wonder if they offered some specifics?


The owners manual says to use "SAE 15W-90 Synthetic Axle Lubricant (GM part Number US 89021677 Meeting GM Specification 9986115)

I called Mobil and asked them if they met that specification with their synthetic 75W-90. They put me on hold for a very short time, came back and said their synthetic gear lube did not meet GM specification and they did not recommend its use. When I called Valvoline, before I could even finish the spec number they said that was a GM specification and none or their gear lubes would meet that specification, I would have to get that one from the dealer. Neither would talk about specifics, I did ask. Honestly, I don't blame them for saying nothing.


FrankN4;

You meant 75W-90 right not 15W-90! The part# you provide and the spec # are for 75W-90.

That is just the GM synthetic 75W-90 "Grape Juice". Nothing special about it whatsoever other than it is synthetic and has limited slip additive/friction modifier in it. Well, unless you think that special grape scent makes it better.

People have been running aftermarket synthetic 75W-90's in place of it without any problems whatsoever. Actually the GM "spec" is not even a techincal spec from what I found out but rather it is a packaging spec according to GM. There is a thread here on this site about it( ie the spec # and what it means ).

Any aftermarket synthetic GL-5 gear oil with the LS additive already in it will be fine. The rear end in your 08( should be a G80 going by the recommended fluid )is the same rear end that was in my 05 and 07(NBS )Silverados and has been used for a long time. Nothing special about the GM fluid called for other than synthetic and that it already has the LS additive in it is the bottom line.

It is not like the special blue GM transfer case fluid( Autotrak II )or the special GM AWD fluid( Versatrak )that have no or limited aftermarket replacement fluids. The "Grape Juice" is easily replaced with aftermarket 75W-90's.

I ran RP MaxGear 75W-90 in both my Silverado's. that called for the exact same fluid as your 08, and it worked fine. No problems, no chatter, no failures, etc... If you prefer Amsoil use their 75W-90( probably the severe gear variety - you can look it up on their site ).

If you are worried about it then just run the GM fluid but you will be paying $25-$30 a bottle vs $15 and less for other alternatives. I would personally throw some RP MaxGear, Amsoil, etc... in there and move on but it is your truck and I respect your decision.


Edited by NHHEMI (01/07/09 05:51 AM)
_________________________
Royal Purple User Since 1990 thumbsup

2014 Jeep Cherokee
"Latitude"
3.2L V6 4WD( ADI )


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#1333513 - 01/07/09 07:06 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: NHHEMI]
FrankN4 Offline


Registered: 04/18/08
Posts: 1093
Loc: Kentucky
 Originally Posted By: NHHEMI

FrankN4;

You meant 75W-90 right not 15W-90! The part# you provide and the spec # are for 75W-90.




I am "GUESSING" Mobil 1's answer is because they make the axle lube for GM and would not think it wise to sell it on their own, especially at a somewhat lower price. I am kind of surprised with their does not meet speck answer, but, that must be a technical answer not an absolute fact answer.

Valvoline/Ashland and Mobil 1 are not on the best of terms so I am guessing Valvoline wanted no part or involvement in anything that could be turned on them. My Silverado does not have the limited slip axle but I noticed that both Mobil 1 and Valvoline synthetic GL5 MT-1 gear oils do have the LS additive.

Thanks for your help and information. I am going to try a search for the thread you mentioned.
_________________________
Actually, I never was as good as I used to be.

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#1333553 - 01/07/09 08:18 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: NHHEMI]
mcrn Offline


Registered: 11/30/05
Posts: 2314
Loc: FL
 Originally Posted By: NHHEMI
 Originally Posted By: FrankN4
 Originally Posted By: Jim Allen
 Originally Posted By: FrankN4
I have a 2008 Silverado that I am getting ready to change the rear axle gear oil. I just today called Mobil 1 about their 75W-90 synthetic and they said it did not meet GM specks. I called Valvoline and they said their 75W-90 synthetic did not meet GM specks, I have not called Amsoil yet but will later today.

If two oil companies say their product does not meet a spec and both recommend using the GM gear oil, I think I am going to do that.


What spec? Is there something new or improved about the '08 that requires some special oil? Just an AAM axle, very much like what's been built for decades and the "official" GM stuff doesn't have a great rep.

I honestly don't understand why someone at either of those companies would tell you what they did but wonder if they offered some specifics?


The owners manual says to use "SAE 15W-90 Synthetic Axle Lubricant (GM part Number US 89021677 Meeting GM Specification 9986115)

I called Mobil and asked them if they met that specification with their synthetic 75W-90. They put me on hold for a very short time, came back and said their synthetic gear lube did not meet GM specification and they did not recommend its use. When I called Valvoline, before I could even finish the spec number they said that was a GM specification and none or their gear lubes would meet that specification, I would have to get that one from the dealer. Neither would talk about specifics, I did ask. Honestly, I don't blame them for saying nothing.


FrankN4;

You meant 75W-90 right not 15W-90! The part# you provide and the spec # are for 75W-90.

That is just the GM synthetic 75W-90 "Grape Juice". Nothing special about it whatsoever other than it is synthetic and has limited slip additive/friction modifier in it. Well, unless you think that special grape scent makes it better.

People have been running aftermarket synthetic 75W-90's in place of it without any problems whatsoever. Actually the GM "spec" is not even a techincal spec from what I found out but rather it is a packaging spec according to GM. There is a thread here on this site about it( ie the spec # and what it means ).

Any aftermarket synthetic GL-5 gear oil with the LS additive already in it will be fine. The rear end in your 08( should be a G80 going by the recommended fluid )is the same rear end that was in my 05 and 07(NBS )Silverados and has been used for a long time. Nothing special about the GM fluid called for other than synthetic and that it already has the LS additive in it is the bottom line.

It is not like the special blue GM transfer case fluid( Autotrak II )or the special GM AWD fluid( Versatrak )that have no or limited aftermarket replacement fluids. The "Grape Juice" is easily replaced with aftermarket 75W-90's.

I ran RP MaxGear 75W-90 in both my Silverado's. that called for the exact same fluid as your 08, and it worked fine. No problems, no chatter, no failures, etc... If you prefer Amsoil use their 75W-90( probably the severe gear variety - you can look it up on their site ).

If you are worried about it then just run the GM fluid but you will be paying $25-$30 a bottle vs $15 and less for other alternatives. I would personally throw some RP MaxGear, Amsoil, etc... in there and move on but it is your truck and I respect your decision.


I have an AWD 03 Yukon. I put the Autotrak II in my transfer case. Should I have put this Versatrak fluid in instead or am I ok? I had never heard of the Versatrak.

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#1333678 - 01/07/09 10:28 AM Re: Silverado 4x4 Differential Fluid Intervals [Re: mcrn]
Ray Offline


Registered: 08/20/03
Posts: 26
Loc: Illinois
My 2004 Silverado 4X4 with locking rear diff. fluid will be changed out with synthetic GL5 75W-90, and no additive will be used. Am I right in doing this? I have not drained the old fluid yet, can anyone tell me how much to buy for replacement? TIA


Edited by Ray (01/07/09 10:30 AM)

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