Rear end oil
06-29-2006, 11:10 AM
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Rear end oil
Im putting another generic 80 in my truck this evening, anyone here know if you need that anti slip additive crap with the G80? I know with the older POSI's GM used you had to use it, but I didnt see any type of clutch system in the G80. Just wondering, I plan to get the oil on the way home, and wont really be able to make another trip if I end up needing it.
06-29-2006, 12:48 PM
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Nope, you don't need an additive with the G80, just 75w-90 synthetic gear oil. (straight from the GM manual, and several parts departments that I've asked to confirm, and a few GM techs that I've also asked to confirm my confirmation, after asking my friend who's a service writer at a Chevy/Hummer dealer who confirmed that my confirmation was correctly confirmed 
...I've double checked a few times)
...I've double checked a few times)
07-01-2006, 11:40 PM
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Actually the G80 from the factory does have clutches. I don't know about aftermarket ones, but the stock ones do. You are correct on the additive, with the synthetic fluid, you do not need the additive per GM. However, if you run regular 80-90, you need to use the additive. I have also had some 'Vettes with ratcheting noise from the rear diff caused by sticky clutches and they run synthetic with no additive. the fix for them is to change the fluid "using the same type" and add a bottle of additive, then go out and do some circles and figure eights to make the clutches slip. If I were you, I'd go ahead and put in the additive, it won't hurt a thing and might save you some trouble later.
The following is from GM Service Information under the Description and Operation of the G80 Locking Differential.
The optional locking differential (RPO G80) enhances the traction capability of the rear axle by combining the characteristics of a limited-slip differential and the ability of the axle shafts to "lock" together when uneven traction surfaces exist. The differential accomplishes this in 2 ways. First by having a series of clutch plates at each side of the differential case to limit the amount of slippage between each wheel. Second, by using a mechanical locking mechanism to stop the rotation of the right differential side gear, or the left differential side gear on the 10.5 inch axle, in order to transfer the rotating torque of the wheel without traction to the wheel with traction. Each of these functions occur under different conditions.
The following is from GM Service Information under the Description and Operation of the G80 Locking Differential.
The optional locking differential (RPO G80) enhances the traction capability of the rear axle by combining the characteristics of a limited-slip differential and the ability of the axle shafts to "lock" together when uneven traction surfaces exist. The differential accomplishes this in 2 ways. First by having a series of clutch plates at each side of the differential case to limit the amount of slippage between each wheel. Second, by using a mechanical locking mechanism to stop the rotation of the right differential side gear, or the left differential side gear on the 10.5 inch axle, in order to transfer the rotating torque of the wheel without traction to the wheel with traction. Each of these functions occur under different conditions.
07-03-2006, 08:04 AM
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Well I got some Castroil 80-90, then noticed the G80 does indeed have clutches, but I didnt use any additive and have no problems, I think the Castroil says it works for Posi units.
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07-03-2006, 08:42 AM
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i went to my local parts store were i get everything from.. they didnt have any synthetic oil. so i got 2 qts of Lucas Oil Stabilizer. i used that along with some 80w-90 my friend had at his shop. My G-80 responds quicker now. she has some miles and abuse on her now.
It was getting where it wouldnt lock at all. so i changed the syn oil with additive to 2 qts of Lucas and what little dino oil it took to top it off.
Now it locks quicker. but thats just a quick fix until i get the Eaton LSD w/ 4.10s.
It still will not lock on the street, dirt, or wet grass, but at the track it will spin both tires???? Go figure....
several months ago i replaced the axle bearings and diff bearings, before i knew that was the problem i mixed Lucas with Synthetic 50/50 and when we took the axles out you could not hold them. they would just slip through your hand, Lucas has got to be the worst stuff! its like snot or something.. its sticky but slippery??
What does Eaton Suggest for the LSD?? need to go ahead and get that before i get the diff and gears in...
It was getting where it wouldnt lock at all. so i changed the syn oil with additive to 2 qts of Lucas and what little dino oil it took to top it off.
Now it locks quicker. but thats just a quick fix until i get the Eaton LSD w/ 4.10s.
It still will not lock on the street, dirt, or wet grass, but at the track it will spin both tires???? Go figure....
several months ago i replaced the axle bearings and diff bearings, before i knew that was the problem i mixed Lucas with Synthetic 50/50 and when we took the axles out you could not hold them. they would just slip through your hand, Lucas has got to be the worst stuff! its like snot or something.. its sticky but slippery??
What does Eaton Suggest for the LSD?? need to go ahead and get that before i get the diff and gears in...
07-03-2006, 10:21 AM
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Originally Posted by nonnieselman
i went to my local parts store were i get everything from.. they didnt have any synthetic oil. so i got 2 qts of Lucas Oil Stabilizer. i used that along with some 80w-90 my friend had at his shop. My G-80 responds quicker now. she has some miles and abuse on her now.
It was getting where it wouldnt lock at all. so i changed the syn oil with additive to 2 qts of Lucas and what little dino oil it took to top it off.
Now it locks quicker. but thats just a quick fix until i get the Eaton LSD w/ 4.10s.
It still will not lock on the street, dirt, or wet grass, but at the track it will spin both tires???? Go figure....
several months ago i replaced the axle bearings and diff bearings, before i knew that was the problem i mixed Lucas with Synthetic 50/50 and when we took the axles out you could not hold them. they would just slip through your hand, Lucas has got to be the worst stuff! its like snot or something.. its sticky but slippery??
What does Eaton Suggest for the LSD?? need to go ahead and get that before i get the diff and gears in...
It was getting where it wouldnt lock at all. so i changed the syn oil with additive to 2 qts of Lucas and what little dino oil it took to top it off.
Now it locks quicker. but thats just a quick fix until i get the Eaton LSD w/ 4.10s.
It still will not lock on the street, dirt, or wet grass, but at the track it will spin both tires???? Go figure....
several months ago i replaced the axle bearings and diff bearings, before i knew that was the problem i mixed Lucas with Synthetic 50/50 and when we took the axles out you could not hold them. they would just slip through your hand, Lucas has got to be the worst stuff! its like snot or something.. its sticky but slippery??
What does Eaton Suggest for the LSD?? need to go ahead and get that before i get the diff and gears in...
The guys at jackson gear and axle suggest dino oil with the additive. If you need some I think I have some extra.
Dock
07-03-2006, 10:27 AM
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yea if you have enough i would surely appreciate it.. im goin to go ahead and get my bearings and oil and prob some seals? just be be safe..
Now i just need to get to the bank to get a Mo so i can get the gears and diff on the way..
when you planning on installing yours dock?
Now i just need to get to the bank to get a Mo so i can get the gears and diff on the way..
when you planning on installing yours dock?