Rear Differential
Thread Starter
Racer
Joined: Nov 2006
Posts: 251
Likes: 0
From: SAN JOSE CALIFORNIA
Rear Differential
I went to buy gear oil for my differenetial (1996), but couldn't find Castrol Syntec Gear Oil. I ran into Redline which stated it was good for Hypoid gear differentials.
1. What are hypoid differnetials (vs. Spiral)? Is that we have?
2. For the Fluild (other than Castrol), any recommondations? (Redline, Mobil1, ...)
TIA,
nogood....
1. What are hypoid differnetials (vs. Spiral)? Is that we have?
2. For the Fluild (other than Castrol), any recommondations? (Redline, Mobil1, ...)
TIA,
nogood....
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
The curved gear teeth in all modern differentials are hypoid.
Most any premium, synthetic gear oil intended for automotive differentials, of the proper weight, will work fine in your C4's differential.
They may need the LSD additive, however....
Larry
code5coupe
Most any premium, synthetic gear oil intended for automotive differentials, of the proper weight, will work fine in your C4's differential.
They may need the LSD additive, however....
Larry
code5coupe
Melting Slicks
Joined: Mar 2001
Posts: 2,978
Likes: 280
From: Tulsa OK
I upgraded the diff in my C5 to a DTE stage 2 setup with 3.90 gears. DTE requires Redline in all the differentials they build to maintain their warranty. When I bought my C4, I changed all the fluids and put Redline plus the GM LSD additive in the diff. 
Le Mans Master
Joined: May 2005
Posts: 5,214
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From: Queensland, AUSTRALIA
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Thread Starter
Racer
Joined: Nov 2006
Posts: 251
Likes: 0
From: SAN JOSE CALIFORNIA
Mobil 1, Royal Purple, Redline
Getting pissed......
In figuring out if I need to add the GM additive, here's what I've found:
-Mobil 1 says:
"...contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required."
"most applications"
-Royal purple says:
"All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary."
C4 are hypoid (not cone), right?
-Redline says:
"It contains friction modifier which is recommended for limited-slip units. "
Ok
Do you guys add the additive anyways?
Harmful if added anyways?
In figuring out if I need to add the GM additive, here's what I've found:
-Mobil 1 says:
"...contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required."
"most applications"
-Royal purple says:
"All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary."
C4 are hypoid (not cone), right?
-Redline says:
"It contains friction modifier which is recommended for limited-slip units. "
Ok
Do you guys add the additive anyways?
Harmful if added anyways?
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
Surely the best amount of additive is the least required to prevent chattering. If people are running Mobil 1 or Redline with no additive and no problems, that must be better, right?
One reason why it would be better is the composition of the lube. The diff takes 2 containers of GM lube and 1 of the additive. The additive is 4 ounces. The GM lube is in 23 ounce containers or 46 ounces for two. That's 50 ounces in total or a lube that is 8% additive. If someone uses 2 containers with Mobil 1, that is 8 ounces of additive and 42 ounces of Mobil 1, a 16% additive mix.
And, of course, the GM lube is not GL-5, it is GL-4. There is a phrase on the bottle that suggest that it is maybe a GL-4+ because it says that some GL-4's won't be good enough.
One reason why it would be better is the composition of the lube. The diff takes 2 containers of GM lube and 1 of the additive. The additive is 4 ounces. The GM lube is in 23 ounce containers or 46 ounces for two. That's 50 ounces in total or a lube that is 8% additive. If someone uses 2 containers with Mobil 1, that is 8 ounces of additive and 42 ounces of Mobil 1, a 16% additive mix.
And, of course, the GM lube is not GL-5, it is GL-4. There is a phrase on the bottle that suggest that it is maybe a GL-4+ because it says that some GL-4's won't be good enough.
Burning Brakes
Joined: Nov 2005
Posts: 1,211
Likes: 2
From: Dumas Arkansas
Don't forget the Mity Vac that you'll need to put the fluid in.
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
I use Castrol Synthetic 80w140 with no additive, no issues with chatter or anything else for that matter. It says on the label of the Castrol Synthetic NOT to use any additive at all.
Chatman, that is some interesting info you state there about what is writen on the bottle, ive honestly never looked at one long enough to read the print. Thanks mate
Chatman, that is some interesting info you state there about what is writen on the bottle, ive honestly never looked at one long enough to read the print. Thanks mate
Thread Starter
Racer
Joined: Nov 2006
Posts: 251
Likes: 0
From: SAN JOSE CALIFORNIA
Ok, my guess is this:
Back in 1996 (or other years for C4), GM is going to recommond their fluid. However, their fluid does not contain the additive as it most likely used in other differentials. So, because our differentials are hypoid/limited slip, GM produced an additive (fricition modifier) and it is required (back in 1996) for use with their fluid.
Present time, most differentials are hypoid/limited sillp and therefore most of the aftermarket fluilds (redline, mobil1, castrol,...) already have such friction modifiers since that's the majority of the market.
So I would guess its okay to "believe" the aftermarket labels ("already contains friction modifiers"). I thought maybe our differentials were something above others (that's why the additive), but a hypoid limited-slip differential is a hypoid limited-slip differential. I think the aftermarket that state it already has the additive will be fine.
I will go with Redline synthetic W/O additive....
What does chatter mean?? Sound like??
Back in 1996 (or other years for C4), GM is going to recommond their fluid. However, their fluid does not contain the additive as it most likely used in other differentials. So, because our differentials are hypoid/limited slip, GM produced an additive (fricition modifier) and it is required (back in 1996) for use with their fluid.
Present time, most differentials are hypoid/limited sillp and therefore most of the aftermarket fluilds (redline, mobil1, castrol,...) already have such friction modifiers since that's the majority of the market.
So I would guess its okay to "believe" the aftermarket labels ("already contains friction modifiers"). I thought maybe our differentials were something above others (that's why the additive), but a hypoid limited-slip differential is a hypoid limited-slip differential. I think the aftermarket that state it already has the additive will be fine.
I will go with Redline synthetic W/O additive....
What does chatter mean?? Sound like??
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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Do you guys add the additive anyways?
Harmful if added anyways?
Surely no one here would intentionally **** up his rear differential.
Harmful if added anyways?
Surely no one here would intentionally **** up his rear differential.
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
