Silverado 4x4 Differential Fluid Intervals

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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?
 
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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
 
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!
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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.
 
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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.
 
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...
smirk2.gif
 
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.
 
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.
 
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.
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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?
 
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).
 
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.
21.gif


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.
 
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.
21.gif


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!
LOL.gif
The part# you provide and the spec # are for 75W-90.
banana2.gif


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.
smirk2.gif


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.
 
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Originally Posted By: NHHEMI

FrankN4;

You meant 75W-90 right not 15W-90!
LOL.gif
The part# you provide and the spec # are for 75W-90.
banana2.gif



blush.gif
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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.
 
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.
21.gif


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!
LOL.gif
The part# you provide and the spec # are for 75W-90.
banana2.gif


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.
smirk2.gif


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.
 
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
 
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Ray--The axle should take about 2.5 quarts. The truck "locking" diffs do not need any extra additive. Their mechanism is different from the clutch-type limited slips.

Trying to find a fluid that meets #9986115 gave me headaches when I changed my 2001. I finally went with Amsoil SVG, and it's working fine.

Did differential drain plugs disappear from the newer trucks like the automatic trans plugs did?
 
Originally Posted By: Rhymingmechanic
Did differential drain plugs disappear from the newer trucks like the automatic trans plugs did?


My neighbor has an '03 Chevy 1500 with an AAM 8.6 rear axle and to my surprise, I found it had a drain plug.
 
2.5 Qts. of oil and no extra additive. Thanks RM.
Mine has a flattened bottom on the case, an obvious place for one, but no drain plug.
 
My 2008 does not have a drain plug. I think I will just get a gasket and remove the cover and do a better job. Mine is not locking or limited slip so I think I will go woth Amsoil or Valvoline gear oil.
 
Originally Posted By: mcrn


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.


The owner's manual will tell you which fluid to use in your T-Case. I would think with the full size vehicle the Autotrak II fluid was the correct choice. I have only seen the Versatrak fluid used in the small SUV's( ie; Equinox, Torrent, Vue ). To be honest I had never heard of it either until I bought the 08 AWD Equinox.
 
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