Redline oil and Limited slip diffs???
08-28-2009, 12:28 PM
#1
Pro
Thread Starter
Redline oil and Limited slip diffs???
I just want to know if I should use 75W-90NS in my trans. It has a slight grind from 3rd to 2nd when the trans is cold, and it's downshifted aggressively. Upshifting at any time/aggression, or downshifting at any time/agression when hot is just fine.
Any suggestions?
I searched many of the threads on pros/cons of redline 75W-90NS trans (gear) oil.
This thread makes it sounds like C4s do NOT have LSDs, relying on the PSM instead, and so the NS-type oils are fine, but you need to run friction modifiers in LSDs.
https://rennlist.com/forums/996-foru...t-the-lsd.html
But then a dude who runs a cup car with an LSD runs the NS oil without issue.
https://rennlist.com/forums/996-gt2-...nsmission.html
Is it a safe bet my car (I just purchased an '01 C4) doesn't have an LSD? (I build 60's and 70s cars, and on a straight axle it's easy to find out, just jack up the rear, trans in neutral, and spin a wheel by hand and see what the other does. But on a transaxle???)
Then there was a link about the redline NS oils (non-slip), being TOO sticky for syncros (link below). Others say it helps them out much better than those oils that have friction modifiers in them. (1%-3% being best).
https://rennlist.com/forums/996-gt2-...dline-oil.html (third post down)
TIA for helping the newbie!!
Any suggestions?
I searched many of the threads on pros/cons of redline 75W-90NS trans (gear) oil.
This thread makes it sounds like C4s do NOT have LSDs, relying on the PSM instead, and so the NS-type oils are fine, but you need to run friction modifiers in LSDs.
https://rennlist.com/forums/996-foru...t-the-lsd.html
But then a dude who runs a cup car with an LSD runs the NS oil without issue.
https://rennlist.com/forums/996-gt2-...nsmission.html
Is it a safe bet my car (I just purchased an '01 C4) doesn't have an LSD? (I build 60's and 70s cars, and on a straight axle it's easy to find out, just jack up the rear, trans in neutral, and spin a wheel by hand and see what the other does. But on a transaxle???)
Then there was a link about the redline NS oils (non-slip), being TOO sticky for syncros (link below). Others say it helps them out much better than those oils that have friction modifiers in them. (1%-3% being best).
https://rennlist.com/forums/996-gt2-...dline-oil.html (third post down)
TIA for helping the newbie!!
08-28-2009, 03:32 PM
#2
Nordschleife Master
The two best gear oils I have run are:
1. The Porsche Shell Transaxle for my 996CAB
2. Mobil Delvac for my track cars (GT3, RS America, Spec Boxster)
1. The Porsche Shell Transaxle for my 996CAB
2. Mobil Delvac for my track cars (GT3, RS America, Spec Boxster)
08-28-2009, 05:17 PM
#3
Racer
Join Date: Jul 2008
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Don't all C4s have LSD? This is the purpose of AWD, a viscus center diff coupling front and rear axles with an open differential would not be very functional.
You could conservatively run OEM fluid which I believe would solve the issue, and fine for street use.
You could conservatively run OEM fluid which I believe would solve the issue, and fine for street use.
08-29-2009, 01:22 AM
#4
per Redline's recommendation I've been running 75-140 in the dif and 75-140NS in the tranny. You can e-mail them youself and ask.
My tranny doesn't like to be shifted fast into 1st and second when cold, but I found that if I let the car warm up a bit longer before taking off on a cold morning it's fine. Changing the fluid from stock to Redline didn't make any difference in that regard (or any other percievable way).
My tranny doesn't like to be shifted fast into 1st and second when cold, but I found that if I let the car warm up a bit longer before taking off on a cold morning it's fine. Changing the fluid from stock to Redline didn't make any difference in that regard (or any other percievable way).
08-29-2009, 11:08 AM
#5
Unfortunately, no. The C4 has a viscous coupling center diff but the rear and front diffs are open. But the C4 comes standard with PSM.
08-29-2009, 02:43 PM
#6
Nordschleife Master
per Redline's recommendation I've been running 75-140 in the dif and 75-140NS in the tranny. You can e-mail them youself and ask.
My tranny doesn't like to be shifted fast into 1st and second when cold, but I found that if I let the car warm up a bit longer before taking off on a cold morning it's fine. Changing the fluid from stock to Redline didn't make any difference in that regard (or any other percievable way).
My tranny doesn't like to be shifted fast into 1st and second when cold, but I found that if I let the car warm up a bit longer before taking off on a cold morning it's fine. Changing the fluid from stock to Redline didn't make any difference in that regard (or any other percievable way).
