THIS SITUATION IS FISHY....

[OtisBlkR1]

In another threat i am asking question about gear lube and transfer case information, Well what happend today warrants a fresh thread and more input (id love to hear from parts counter people on this.

So I take my fresh information i learned in another thread on BITOG and head to the dealer to pick up Autotrack 2 and gear lube.

After walking out to my truck and copying my VIN # and Bringing up REF1-277 10/24/2006 (i have the papers in front of me)

Chevrolet parts department (big dealer and parts dept) Did not stock 80/90 wt front diff fluid #89021671 (I found this strange) and the Parts man was scratching his head, the closest parts shop that had it in stock was 30 miles away in a small country town

So i asked if i could just put the 75/90 SYN in the front and be done with it.. Parts guy said he had to go ask one of the mechanics.. He returned and said "Chevy has this part number and this weight for a reason, the mechanic does not think its wise to differ from the recomended fluid"

I found this strange..

SO, about that time another mechanic walks into the parts dept and a conversation between the two mech-Parts man starts.

I chime in and ask the mechanic

ME: "Hey, can i just put 75/90 syn in my front diff on my 06 silverado 1500 5.3 ?"

Mechanic: "sure thats what we do here"

ME: is there anything special about the AC Delco you guys sell or am i safe choosing of the rack like Valvoline, Mobil, ect..

Mechanic: NO you wanna use the AC-Delco, alot of the others put a additive in there that can destroy your clutches *clutches*
ME: ok thanks (thinking this mechanics off his rocker what clutches are in a differential ?

Mechanic exits..

ME, Ok set me up i need a total of 5 quarts of 75/90 AC-Delco..

Parts guys is very hesitant at this point, he speaks up and say's err, i gave you a 10% discount but its still $31.00 a quart, so with your Autotrack 2 and 5 quarts of 75/90 its a total of $170.00 (estimated)..

SO, at this point the BITOG gears in my head kick in and think i should bring this to you all..

I stop at NAPA shortly after and find SYN 75/90 FOR $12.99
AND 80/90 for less than that..

SO, somethings Fishy.. were talking a close to $20.00 price gap on gear oil, is this just simply massive dealer markup ?
Is there absolutely any reason i cant buy the valvoline 80/90 gear oil for my front and VALVE SYN 75/90 for my rear ?
Is there any difference between the Valvoline SYN and the AC-Delco syn ? (remember the mechanic said only AC)... ??fISHY??

the NAPA parts guy thought this story was "funny" and stated there were no complaints from other users on His *Napa/Valvoline* gear oil.

the last eight of my VIN 6z224678

I know this is a lengthy post and im 99% sure your all going to tell me that the NAPA valveoline is fine.. but i have two more questions.

#1 do i HAVE to use 80/90 gear oil in the front ? or is 75/90 ok (im sure its ok, just confirming)

#2 Im pretty sure my truck is a limited slip 99% so i dont need to add anything to the gear oil correct ? thats only for possi track's ?

Ok long winded post over.. knowledgeable replies please !

 

[exranger06]

Some limited slip differentials are clutch-based. They require a friction modifier added to the fluid to work properly. A lot of gear oils have this modifier already added to the fluid. That's what the mechanic was talking about. I don't know if yours requires any modifier.

You can definitely use 75w-90 instead of 80w-90.

 

[UNC151]

Originally Posted By: exranger06
Some limited slip differentials are clutch-based. They require a friction modifier added to the fluid to work properly. A lot of gear oils have this modifier already added to the fluid. That's what the mechanic was talking about. I don't know if yours requires any modifier.

You can definitely use 75w-90 instead of 80w-90.

+1 - also remember that AC-Delco (just like Ford and Chrysler) does not manufacture oil, it is bottled by one of the big oil producers. Other than the additives that may be in the oil for the limited slip "clutch packs", there is nothing special about AC-Delco oil. You can use the 75W-90 with no issues; if you can find some Mobil 1 gear oil it already has the additives in it (as do many of the other synthetic gear oils).

 

[Turk]

Originally Posted By: 2010_FX4
+1 - also remember that AC-Delco (just like Ford and Chrysler) does not manufacture oil, it is bottled by one of the big oil producers. Other than the additives that may be in the oil for the limited slip "clutch packs", there is nothing special about AC-Delco oil. You can use the 75W-90 with no issues; if you can find some Mobil 1 gear oil it already has the additives in it (as do many of the other synthetic gear oils).

+1, +1.

I got the same rear diff as you and I have ran Amsoil Slip-Lock & Amsoil Severe Gear fluid with 3 changes since 30,000 miles & I have over 183,000 miles on it!

Not one issue!

 

[01rangerxl]

75W90 is fine where 80W90 is called for. I have done it multiple times on multiple trucks.

If your truck has a limited slip differential, it would have friction material inside that requires a friction modifier in the fluid. $31 a quart is insane though. You can get a bottle of friction modifier by itself for about $10, just add it to the diff with the $12.99 a quart fluid. I would GUESS though that your truck has an open front differential, and a G80 locker in the rear (check RPO codes). Neither one would need friction modifiers, even the G80. I think synthetic is required/suggested for the G80, but I'm not positive on that.

 

[dave1251]

You are good to go! I have nothing else to add other than this did entertain me for a good 5 minutes.

 

[QuietPortage]

I just got six quarts of M1 75w-90 at Advance Auto Parts for about $50. You can use their $15 off $50 discount code. Not a bad deal.

 

[morris]

why didnt the mechanic say, " the factory service manual says............." i would not want a mech that cant read the factory manual , give advice or work on my machine. course i have seen mistakes in factory service manuals. course i don't all ways do what the factory service manual says, but i dont do those things on a whim i think about it a LOT before i do those things.

 

[OtisBlkR1]

my paperwork the chevy dealer printed off for me via my VIN says this

REF1-168 03/29/2006

2006 CHEROLET SILVERADO c 2WD, k 4WD

FRONT DRIVE AXLE (8.25")
REAR DRIVE AXLE(8.6")

this is what the parts man says i have..

REF1-277 10/24/2006

Pickup models: rear axle (SAE 75W-90 Synthetic) ( 1 quart)
Pickup models: Front axle (SAE 80W-90) (24OZ)

REF1-234 10/18/2006

Front Axle 89021671 (SAE 80/90) *same part number for HD trucks*
Rear Axle 89021677(SAE 75W-90 synthetic)

Im sure i have the limited slip differential, that being the case i need to buy a gear oil with the additive already added (pref) ?

This is awfully complicated for doing a diffferential service myself.. sheesh..

 

[Kestas]

I too use synthetic 75W-90 where 80W-90 is called for.

I just wanted to mention that the first mechanic didn't know better, and considering his lack of experience, was correct to cite the manual requirements. When not sure, it's always good to default to what the manual says.

 

[Loobed]

General Motors (Chevy and GMC) uses 80w-90 in the front because it costs less than 75w-90 and the 80w-90 is all that is needed. GM may save $0.50 or more per fill per vehicle. If you add up 50 cents x 1,000,000 vehicles, you see that it starts to save a lot of money.

For the front axle you will need about 1.8 qts, so get 2 qts, and you will have some left over. I think 75w-90 is better oil, but you will not see an improvement in mileage, so if you have to save a few dollars use 80w-90 in the front. If you use 80w-90 you can change your oil twice as often. This is great if have BITOG OCLCD (obsessive compulsive lube change disorder)

The rear differential is a G-80 type, and uses carbon fiber clutch disks. 75w-90 is the only fluid that will work with those clutches. You need at least 2.5 qts, so buy 3. You can get some high quality RedLine for $15 a quart. I believe most NAPA stores sell it: All the ones around here sell it. If you are paying more than ~$16 a quart, you are paying too much. I believe Mobil 1 75w-90 is under $10 a quart. My GMC didn't like Mobil 1 or Valvoline synthetic in the rear. The front differential wasn't any different.

The Red Line lube that works for you truck is here:
http://www.redlineoil.com/product.aspx?product=57904

I will be trying out ENEOS 75w-90 lube in the front this summer. You can get 5 quarts on ebay for $60 shipped: 3 quarts $38. Eneos 75w-90 link
I do not know how well Eneos will work in the rear, but it should work.

 

[RF Overlord]

Originally Posted By: OtisBlkR1
#1 do i HAVE to use 80/90 gear oil in the front ? or is 75/90 ok (im sure its ok, just confirming)

#2 Im pretty sure my truck is a limited slip 99% so i dont need to add anything to the gear oil correct ? thats only for possi track's ?
#1 - 75W90 is fine for the front axle.

#2 - "Posi", short for "Positraction", is simply GMs vernacular for limited slip. Ford calls their version "Traction-Lok" or "Trac-Lok". They're all the same thing. As for the friction modifier, most of the major brand fluids have it already in them, but it will usually say so on the bottle.

 

[OtisBlkR1]

"""#2 - "Posi", short for "Positraction", is simply GMs vernacular for limited slip. Ford calls their version "Traction-Lok" or "Trac-Lok". They're all the same thing. As for the friction modifier, most of the major brand fluids have it already in them, but it will usually say so on the bottle"""

OK


While at Napa the Valvoline SYN 75/90 with little flyer on the bottle saying (friction additive) or something to this effect was what i was looking at.

AND

"""""I believe Mobil 1 75w-90 is under $10 a quart. My GMC didn't like Mobil 1 or Valvoline synthetic in the rear. The front differential wasn't any different."""""

can you tell me how your rear differential was not acting correctly ? this way i know what to look/listen for if my Silverado does not care for one or both of these brands..

 

[OtisBlkR1]

ALSO: im changing these fluids every 30,000 i can see the diff's needing changed that often but di i truly need to change my transfer case every 30,000 ? ive only used the 4x4 a couple dozen times in the past four years.. seems a little silly to me, your thoughts ?

 

[OtisBlkR1]

General Motors (Chevy and GMC) uses 80w-90 in the front because it costs less than 75w-90 and the 80w-90 is all that is needed. GM may save $0.50 or more per fill per vehicle. If you add up 50 cents x 1,000,000 vehicles, you see that it starts to save a lot of money.

For the front axle you will need about 1.8 qts, so get 2 qts, and you will have some left over. I think 75w-90 is better oil, but you will not see an improvement in mileage, so if you have to save a few dollars use 80w-90 in the front. If you use 80w-90 you can change your oil twice as often. This is great if have BITOG OCLCD (obsessive compulsive lube change disorder)

The rear differential is a G-80 type, and uses carbon fiber clutch disks. 75w-90 is the only fluid that will work with those clutches. You need at least 2.5 qts, so buy 3. You can get some high quality RedLine for $15 a quart. I believe most NAPA stores sell it: All the ones around here sell it. If you are paying more than ~$16 a quart, you are paying too much. I believe Mobil 1 75w-90 is under $10 a quart. My GMC didn't like Mobil 1 or Valvoline synthetic in the rear. The front differential wasn't any different.

The Red Line lube that works for you truck is here:
http://www.redlineoil.com/product.aspx?product=57904

I will be trying out ENEOS 75w-90 lube in the front this summer. You can get 5 quarts on ebay for $60 shipped: 3 quarts $38. Eneos 75w-90 link
I do not know how well Eneos will work in the rear, but it should work. [/quot


Thanks, just ordered 5 quarts of redline ! good tip.

 

[Loobed]

Originally Posted By: OtisBlkR1

"""""I believe Mobil 1 75w-90 is under $10 a quart. My GMC didn't like Mobil 1 or Valvoline synthetic in the rear. The front differential wasn't any different."""""

can you tell me how your rear differential was not acting correctly ? this way i know what to look/listen for if my Silverado does not care for one or both of these brands..




When I went around corners my rear end would chatter. It almost felt like there was rocks in the differential. A few times I heard a heavy clunk and it felt like someone hit me from the side. Valvoline was the worst. Mobil 1 worked a little better, but it still had a little chatter. Amsoil worked great for over 30,000 miles, but I eventually heard some chatter, so I poured a bottle of GM limited slip s=additive, and so far the chatter hasn't been back. I never had problems with the factory fill fluid, but it costs to much so I trued other stuff.

 

[Loobed]

Originally Posted By: OtisBlkR1
ALSO: im changing these fluids every 30,000 i can see the diff's needing changed that often but di i truly need to change my transfer case every 30,000 ? ive only used the 4x4 a couple dozen times in the past four years.. seems a little silly to me, your thoughts ?


The transfer case gears/belts run continuously even if you are not in 4 wheel drive. You can wait until 50,000 miles to change the fluid.

 

[SteveSRT8]

Our policy is transfer cases with real hypoid gear oil can easily go much farther than newer ones with atf.

One thing is for certain, if you have a clutch type posi you MUST use posi fluid or additive. Sometimes both if it's tight.

 

[Loobed]

Originally Posted By: SteveSRT8
Our policy is transfer cases with real hypoid gear oil can easily go much farther than newer ones with atf.

One thing is for certain, if you have a clutch type posi you MUST use posi fluid or additive. Sometimes both if it's tight.



The newer (1999+) GM auto-switching (or whatever it is called) transfer cases MUST use Auto-Trak 2 fluid. You might be able to use something else, but GM claims to have put a voodoo curse on it and if you don't use the specific fluid, you will end up with a zombie transfer case.

The G-80 locker differential in GM trucks does not need the limited slip additive (it won't hurt to add it). It doesn't use the conventional type of locking system like the older styles. I am not sure of the exact make-up.


here is a quote I got off another site about the G-80 locker: "Lockers are open until you lock them together. Limited slips are held together by a viscous clutch all the time. The Gov Lock is what's in between; open for 90% of the time, but a viscous limited slip when needed."

 

[MrHorspwer]

Do a search for TSB 09-04-19-002

The long and short, it's a TSB that specifically indicates using 75W-90 synthetic (P/N 89021677) in place of 80W-90 on 1500 trucks with an 8.5" front axle. The TSB is to correct poor 4WD shift performance in cold ambient temps.

Even so, that is a direct recommendation from GM that it's alright to use synthetic 75W-90 in the front axle of your truck. Doesn't get much clearer than that.