Limited Slip Additive
Thread Starter
Safety Car
Joined: Sep 2002
Posts: 4,161
Likes: 12
From: San Diego CA
Limited Slip Additive
What does it do?
I drained my trans and rear today and had synthetic Mobil 1 ATF and 75/90 gear lube ready to go. I stopped by my local GM dealer but of course they were out of the additive and I couldn't finish the job. I'm sure I'll find some tomorrow and I was wondering what the additive does for the rear end.
I drained my trans and rear today and had synthetic Mobil 1 ATF and 75/90 gear lube ready to go. I stopped by my local GM dealer but of course they were out of the additive and I couldn't finish the job. I'm sure I'll find some tomorrow and I was wondering what the additive does for the rear end.
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid.
Dave
Drifting
Joined: Aug 2002
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From: South
Originally Posted by TT_Vert
Thanks for the info.
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
np, u can still put it in if you'd like. I havent for years and never had a problem w/ premature diff wear from mustangs w/ solid rears to c5s w/ the IRS rear. If you go w/ the GM lube, you must use the Friction modifier however.
Dave
Dave
Thread Starter
Safety Car
Joined: Sep 2002
Posts: 4,161
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From: San Diego CA
From Mobile 1:
"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid."
I'll add the GM stuff. Couldn't hurt but probably not absolutely necessary.
"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid."
I'll add the GM stuff. Couldn't hurt but probably not absolutely necessary.
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Race Director
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From: Now in God's Country, the Big Sky, Montana!
Cruise-In 7-8-9-10 Veteran
St. Jude Donor '06-'07-'08-'09-'10-'11-'12
Originally Posted by TT_Vert
redline and many synthetics have the friction modifier in it already.
dave
dave
Safety Car
Joined: Sep 2001
Posts: 4,411
Likes: 1
From: Wilmington NC
Originally Posted by jmzvet
From Mobile 1:
"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid."
I'll add the GM stuff. Couldn't hurt but probably not absolutely necessary.
"Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid."
I'll add the GM stuff. Couldn't hurt but probably not absolutely necessary.
Pro
Joined: Nov 2002
Posts: 599
Likes: 16
From: vista CA
I tried to switch to Mobil 1 syn gear lube (with one bottle of additive) on my 98 - but after a few weeks starting getting weird noises from rear end 
. After several trips to dealer (still under warrenty) finally flushed out Mobil 1 and went with stock gear lube and one bottle of additive - much better! Still had a little noise on figure 8's and put in a second bottle of additive myslef - have not had any sounds / issues in the diff now for over 25k miles, year and a half.
I believe a few others also had problems with switching to mobil 1 syn gear lube in diff - I had ~30kmiles on a 4 or 5 year old C5. But - many have not had issues with Mobil 1 syn gear lube. Just keep this in mind if you do switch, might save some trouble if you have problems.
. After several trips to dealer (still under warrenty) finally flushed out Mobil 1 and went with stock gear lube and one bottle of additive - much better! Still had a little noise on figure 8's and put in a second bottle of additive myslef - have not had any sounds / issues in the diff now for over 25k miles, year and a half.I believe a few others also had problems with switching to mobil 1 syn gear lube in diff - I had ~30kmiles on a 4 or 5 year old C5. But - many have not had issues with Mobil 1 syn gear lube. Just keep this in mind if you do switch, might save some trouble if you have problems.
Pro
Joined: Nov 2002
Posts: 599
Likes: 16
From: vista CA
Originally Posted by nmbis2k
Martin - isn't the stock GM gear lube a synthetic product...or at least semi-synthetic?? thanks..
Safety Car
Joined: Sep 2001
Posts: 4,411
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From: Wilmington NC
Originally Posted by nmbis2k
Martin - isn't the stock GM gear lube a synthetic product...or at least semi-synthetic?? thanks..
GM switched from conventional to synthetic very early in C5 production. By late 97 all cars came out of the factory with synthetic.
I switched to Redline 75W/90 after about 15,000 miles. Redline has about 4% friction modifier built in and I have never had to add any more.
Team Owner
Joined: Mar 1999
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From: At the beach in little Rhody
Originally Posted by Richin Chicago
Be careful with adding more friction modifier. The way to really fine tune this process is to hear some chatter and add just enough friction modifier to eliminate it. Too much modiifer will cause the plates to slip all the time and you will have no limited slip capability.
I use Amsoil that has the modifier in it. Redline makes two rear oils, 75W-90 that has the modifier in it, and 75W-90NS that does not. You can obtain the correct slip characteristics by using some combination of the above or using the NS and adding the modifier. The point is, too much and you effectively do not have a limited slip differential any more. This is one case where more is not necessarily better.
