Silverado 4x4 Differential Fluid Intervals

[NHHEMI]

Originally Posted By: FrankN4
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.


You should be fine.

 

[Jim 5]

Originally Posted By: NHHEMI
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.



Are you sure it's an AWD and not a 4WD?

It would have to be a Yukon Denali to be an all wheel drive. If it is a regular Yukon with a selectable transfer case (eg. with the buttons to the left of your steering wheel), then it is a 4WD and you use autotrakII. Like others said, rely on your owner's manual for the final word.

 

[Steve S]

Change the oil now.

 

[Jim 5]

Originally Posted By: Jim Allen
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.


GM phased out a bunch of stuff in their 2004 trucks as a cheesy cost cutting measure. The ones I'm aware of included:

- second sun visors (driver and passenger side)
- underhood light
- rear diff drain plugs

I'd have gladly paid an extra $50 for all of those options, which is probably double or triple what they actually saved by eliminating them.

 

[FrankN4]

FOR ENTERTAINMENT PURPOSES ONLY

I have been trying to follow up on this as best as I could. In searching every search word or string that came to mind, I wound up at a GM truck forum, a Chevrolet truck forum, a Cadillac forum, a Corvette forum, GM Goodwrench, a forum called Edmunds, and a few other places. One of the forums has an actual GM TSB. From that very scant TSB and what everyone is saying, it seems that the 9986115 GM spec has four specifics:

1. Exceptional cold flow properties and fuel conserving. One
reply from an oil company said they did not meet specs
because their 75W-90 had a higher 40C and 100C cSt. It seems
the GM spec axle lube is to axle lube what 5W-20 is to motor
oil.

2. Proprietary friction modifiers for limited slip applications.

3. Low sulphur but phos above 2500 and zinc above 2500. Comments
and opinions seemed to indicate that GM axle did not like
"iron sulfide" I am not chemistry minded enough to know but
I am thinking regular axle lubes actually plate gear teeth
with a very hard iron sulfide coating but this can cause c
corrosion especially if there are copper/bronze components.

4. The GM spec has "special seal conditioners." Opinions seemed
to run toward believing GM may have changed/used a different
seal material than the norm, whatever that is.

Again, this is from searching, listening to opinions, one GM tech person, one scant GM TSB, a response from Eaton, and a response from two oil companies. I do not represent it to be fact, just what many/popular opinion is thinking and why they seem to think that way.

 

[artificialist]

Originally Posted By: FrankN4
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.

This is a good time to blast the gears and bearings with some carb or brake cleaner to remove the gray slime that is iron shed by gear wear.

 

[kgcobra320]

Originally Posted By: FrankN4
FOR ENTERTAINMENT PURPOSES ONLY

I have been trying to follow up on this as best as I could. In searching every search word or string that came to mind, I wound up at a GM truck forum, a Chevrolet truck forum, a Cadillac forum, a Corvette forum, GM Goodwrench, a forum called Edmunds, and a few other places. One of the forums has an actual GM TSB. From that very scant TSB and what everyone is saying, it seems that the 9986115 GM spec has four specifics:

1. Exceptional cold flow properties and fuel conserving. One
reply from an oil company said they did not meet specs
because their 75W-90 had a higher 40C and 100C cSt. It seems
the GM spec axle lube is to axle lube what 5W-20 is to motor
oil.

2. Proprietary friction modifiers for limited slip applications.

3. Low sulphur but phos above 2500 and zinc above 2500. Comments
and opinions seemed to indicate that GM axle did not like
"iron sulfide" I am not chemistry minded enough to know but
I am thinking regular axle lubes actually plate gear teeth
with a very hard iron sulfide coating but this can cause c
corrosion especially if there are copper/bronze components.

4. The GM spec has "special seal conditioners." Opinions seemed
to run toward believing GM may have changed/used a different
seal material than the norm, whatever that is.

Again, this is from searching, listening to opinions, one GM tech person, one scant GM TSB, a response from Eaton, and a response from two oil companies. I do not represent it to be fact, just what many/popular opinion is thinking and why they seem to think that way.


So, all of this taken into consideration what should I put in my 2008 Colorado Z71 differentials?

I would like superior lubrication/performance over OEM fluids and personally consider cost as not an issue but rather relatively cheap insurance. However, I don't want to void my warrantee either.

KG

 

[FrankN4]

kg

I feel exactly the same way. I think I need to learn more about chemistry. IF the GM lube is sulphur free, it must be for a reason. What I can not find out for sure is whether it is or is not sulphur free.

My truck is only 10 months old and has only 4935 miles. I will change the axle, transmission fluid and filter, and oil and filter, again, next week. I guess I will just chicken out and use GM as I dare not take a chance on warranty, especially if I cause any damage by using a POSSIBLE CORROSIVE LUBE.

However, if it is sulphur free with seal conditioners, I would be great for Honda shaft drive motorcycles.

 

[FrankN4]

kg Look at this. Should answer our questions. Isn't it amazing how a few facts can change things?

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1360129&gonew=1#UNREAD

 

[Jason2007]

I used to own a 06 Silverado 4x4 and I ran RP 75w90 in both diffs with no problem whatsoever.

 

[NHHEMI]

Originally Posted By: Jason2007
I used to own a 06 Silverado 4x4 and I ran RP 75w90 in both diffs with no problem whatsoever.


05 & 07 running the same RP 75W-90. No issues either.

 

[kgcobra320]

Fn4,
So we can try and find a fluid with similar properties or just go with the GM stuff.

I really wish that the aftermarket companies would just look at the GM spec and determine if they meet it or not. It sure would be a lot easier. I would just use the GM fluid but my gut tells me that the OEM is not as good as the best aftermarket fluids.

KG

 

[kgcobra320]

Originally Posted By: NHHEMI
Originally Posted By: Jason2007
I used to own a 06 Silverado 4x4 and I ran RP 75w90 in both diffs with no problem whatsoever.


05 & 07 running the same RP 75W-90. No issues either.


NHHEMMI,

Do you know how the RP fluid compares to the GM fluid or if it meets the GM spec?

KG

 

[1sttruck]

Service intervals for axles are interesting. My Dodge uses AAM axles, same as GM, and for severe duty it has a 15k interval and no interval for regular duty. I did 15k initially, would have done it earlier as the fluid look like black snot, but the next 15k and next 30k looked like a darker olive oil. I use M1 75W90.

 

[kgcobra320]

Originally Posted By: 1sttruck
Service intervals for axles are interesting. My Dodge uses AAM axles, same as GM, and for severe duty it has a 15k interval and no interval for regular duty. I did 15k initially, would have done it earlier as the fluid look like black snot, but the next 15k and next 30k looked like a darker olive oil. I use M1 75W90.


My brother has been a heavy equipment mechanic at a construction company for quite a few years now and he reccomends that the axle fluids should definately be changed after the first 1000-2000 miles. The reason being is that there are a lot of break-in particulates/byproducts generated during this time. This is probably the reason your fluid looked so bad at the first change interval.

KG

 

[NHHEMI]

Originally Posted By: kgcobra320
Originally Posted By: NHHEMI
Originally Posted By: Jason2007
I used to own a 06 Silverado 4x4 and I ran RP 75w90 in both diffs with no problem whatsoever.


05 & 07 running the same RP 75W-90. No issues either.


NHHEMMI,

Do you know how the RP fluid compares to the GM fluid or if it meets the GM spec?

KG


RP MaxGear oils are a compatible replacement for GL-4 & GL-5 gear oils. I don't have the exact spec's for the GM and RP fluids to compare but there are countless thousands of people running RP, Amsoil, Redline, etc... fluids in place of the Grape Juice without any issues. The GM stuff is nothing great and is extremely over priced. As said I have run the RP 75W-90 in place of the GM stuff with zero issues.