Getting ready to open up the rear end.
You're right that the limited slip is the type of rear end but they use a special fluid. When you go to the parts store next to the rear end fluid there will be a small tube of fluid that says limited slip additive you need to put that in with your fluid unless the fluid says safe for limited slip rear end
This is right off of GM SI(service information)
Differential SAE 80W-90 GL-5 gear lubricant or equivalent.
add 118 ml (4.0 fl. oz.) of limited slip differential additive.
Drain and Refill 1.7 liters (3.5 pt)
Additive 118 milliliters (4.0 fl oz)
Differential SAE 80W-90 GL-5 gear lubricant or equivalent.
add 118 ml (4.0 fl. oz.) of limited slip differential additive.
Drain and Refill 1.7 liters (3.5 pt)
Additive 118 milliliters (4.0 fl oz)
The House is Rockin'
Joined: Mar 2008
Posts: 2,577
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From: Under a moaning senorita
just go with the mobil1 that already has it added in
http://www.mobiloil.com/USA-English/..._75W-90LS.aspx
http://www.mobiloil.com/USA-English/..._75W-90LS.aspx
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
You're right that the limited slip is the type of rear end but they use a special fluid. When you go to the parts store next to the rear end fluid there will be a small tube of fluid that says limited slip additive you need to put that in with your fluid unless the fluid says safe for limited slip rear end
Yeah limited slip and posi are the same thing just different names. If you want to get really technical there are some differences but most people just use the names interchangeably
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
Cool I love to learn new thing every day you all helped out a lot. Now I get to have the fun of tearing it apart and finding out what is in there. One more thing. What size gears can I pray to find?
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Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
I have an auto. so I am hoping for 3.73. Now me and some friend sware there is a cam that has been put in. Don't know which one, but would that change what gear size he might have put in.
And if it's been cammed, it will have a much more distinct lope to it. You might want to just pop off a valve cover to see (although if you posted an audio clip, all of us could tell you).
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Look at the RPO code to see what the car came with. RPO codes are three digits, and are listed either in the door jamb or in the glove box.
GU2 = 2.73
GU5 = 3.23
I would be careful in throwing synthetic fluid in an older differential, where you don't know what was in it previously. I was discussing this with either a Quaker State or Valvoline tech rep, right after I put syn diff oil in a Caprice LTZ my wife used to have. The car had 50,000 miles on it at the time I was switching to the syn oil, and he told me that there might be leakage issues, if the additives in the syn oil didn't adapt well to the seals that had seen several years of use with regular oil. We got into this discussion because I wasn't sure if I needed the "posi additive" with the syn oil. (I did)
Something to consider also, is using RedLine diff oil, as it already has the additive in it, as long as you don't get the "Non-LS" oil, which is for open diffs. Another caution, based on my experience, I used to have an S-10 4x4 for a winter vehicle. I put valvoline syn oil in the diffs shortly after I bought the truck. A few years later, I wanted to change it, just for the sake of maintenance. The store was out of Valvoline, so I bought Mobil 1 instead. Shortly thereafter, the rear diff pinion seal started "seeping" oil. Coincidence???
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
"Limited slip" is a type of differential that applies torque to both rear wheels under hard acceleration, therefore limiting wheel slippage compared to an "open" differential that just lights up one tire. "Positraction" or "posi" for short, is what Chevrolet called its "limited slip" rear axle. Pontiac called it "Safe-T-Track", Ford called it "Equa-Lock", Chrysler called it "SureGrip", etc.......
I would be careful in throwing synthetic fluid in an older differential, where you don't know what was in it previously. I was discussing this with either a Quaker State or Valvoline tech rep, right after I put syn diff oil in a Caprice LTZ my wife used to have. The car had 50,000 miles on it at the time I was switching to the syn oil, and he told me that there might be leakage issues, if the additives in the syn oil didn't adapt well to the seals that had seen several years of use with regular oil. We got into this discussion because I wasn't sure if I needed the "posi additive" with the syn oil. (I did)
Something to consider also, is using RedLine diff oil, as it already has the additive in it, as long as you don't get the "Non-LS" oil, which is for open diffs. Another caution, based on my experience, I used to have an S-10 4x4 for a winter vehicle. I put valvoline syn oil in the diffs shortly after I bought the truck. A few years later, I wanted to change it, just for the sake of maintenance. The store was out of Valvoline, so I bought Mobil 1 instead. Shortly thereafter, the rear diff pinion seal started "seeping" oil. Coincidence???
I would be careful in throwing synthetic fluid in an older differential, where you don't know what was in it previously. I was discussing this with either a Quaker State or Valvoline tech rep, right after I put syn diff oil in a Caprice LTZ my wife used to have. The car had 50,000 miles on it at the time I was switching to the syn oil, and he told me that there might be leakage issues, if the additives in the syn oil didn't adapt well to the seals that had seen several years of use with regular oil. We got into this discussion because I wasn't sure if I needed the "posi additive" with the syn oil. (I did)
Something to consider also, is using RedLine diff oil, as it already has the additive in it, as long as you don't get the "Non-LS" oil, which is for open diffs. Another caution, based on my experience, I used to have an S-10 4x4 for a winter vehicle. I put valvoline syn oil in the diffs shortly after I bought the truck. A few years later, I wanted to change it, just for the sake of maintenance. The store was out of Valvoline, so I bought Mobil 1 instead. Shortly thereafter, the rear diff pinion seal started "seeping" oil. Coincidence???
My suggestion would be this.... Remove the diff cover, and let the oil drain out. Look at it as it drains. GM usually adds some sort of a "moly" based additive to their rear ends from the factory, and it tends to make the oil dark and gray. If the oil you drain is this color, it's most likely the original oil, and most likely regular oil, not synthetic. Keep in mind, your car is 16 years old, and not too many people go to the trouble of changing gear oil, so the odds are that the "OE oil" is in there.
If that's the case, replace the oil with regular 80W-90 gear oil, along with a 4 oz. bottle of the Positraction additive, and enjoy!!
A hint from my years of experience....when the oil drains out, it cascades over the bolt holes in the lower part of the diff casting. Some of that oil will creep into the holes, and then seep back out when you install the bolts. That seeping oil usually causes a leak, as it wets the gasket, or the RTV if you use just that, while you're putting the cover back in place. If you have access to compressed air, blow the oil out of the holes before you replace the bolts. If not, use a few q-tips to clear the oil out....
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
My suggestion would be this.... Remove the diff cover, and let the oil drain out. Look at it as it drains. GM usually adds some sort of a "moly" based additive to their rear ends from the factory, and it tends to make the oil dark and gray. If the oil you drain is this color, it's most likely the original oil, and most likely regular oil, not synthetic. Keep in mind, your car is 16 years old, and not too many people go to the trouble of changing gear oil, so the odds are that the "OE oil" is in there.
If that's the case, replace the oil with regular 80W-90 gear oil, along with a 4 oz. bottle of the Positraction additive, and enjoy!!
A hint from my years of experience....when the oil drains out, it cascades over the bolt holes in the lower part of the diff casting. Some of that oil will creep into the holes, and then seep back out when you install the bolts. That seeping oil usually causes a leak, as it wets the gasket, or the RTV if you use just that, while you're putting the cover back in place. If you have access to compressed air, blow the oil out of the holes before you replace the bolts. If not, use a few q-tips to clear the oil out....
If that's the case, replace the oil with regular 80W-90 gear oil, along with a 4 oz. bottle of the Positraction additive, and enjoy!!
A hint from my years of experience....when the oil drains out, it cascades over the bolt holes in the lower part of the diff casting. Some of that oil will creep into the holes, and then seep back out when you install the bolts. That seeping oil usually causes a leak, as it wets the gasket, or the RTV if you use just that, while you're putting the cover back in place. If you have access to compressed air, blow the oil out of the holes before you replace the bolts. If not, use a few q-tips to clear the oil out....
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
Actually, most autos got 2.73s. This will make a difference when upgrading. The 2.73 is a 2 series carrier and the 3.23 is a 3 series carrier.
Look at the RPO code to see what the car came with. RPO codes are three digits, and are listed either in the door jamb or in the glove box.
GU2 = 2.73
GU5 = 3.23
Look at the RPO code to see what the car came with. RPO codes are three digits, and are listed either in the door jamb or in the glove box.
GU2 = 2.73
GU5 = 3.23
