Road Racing - Redline 75w140NS without friction modifier

In prep for track day this weekend I used Redline 75w140NS. No friction modifier. It's the first time I used 140 but I've used 90w Redline NS in the past. I do have some noisy clutch packs in slow turns right now that I didn't have before. I chalk it up to the heavier weight and the cooler temps. Once the diff gets some heat in it the clutches quiet down. The interesting thing is leaving the friction modifier out.....on purpose. There appears to be a performance benefit and my local race car builder recommends NS for the track if you have a clutch pack type limited slip. Here is what Redline says about NS "Also used in clutch-type limited slip differentials in racing for maximum lock up-some users add Limited Slip Friction Modifier in small doses to customize slippage". . Interesting. I plead ignorance because I never new NS had no friction modifier. I just blindly did what I was told . Good to know that the sometimes noisy clutches will not cause permanent damage (??). http://69.89.75.22/product.aspx?pid=39&pcid=4

Here is a blurb from our CTS V mod pioneers UUC on the Redline NS. "75W140NS Manual Transmission Lubricant; A heavier product what works well over a wide range of loads and temperatures, This GL-5-type gear oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin". http://www.uucmotorwerks.com/catalog...e-75w140ns.htm

So for a street car that sees a lot of track time is there a concern when skipping the friction modifier or dosing it as an option? I have an HPD car that sees limited street time.

The NS designation stands for "non slip" of course. Use it and add the Friction Modifier as needed (none or very little) until you can stand the chatter in low speed cool differerential type turns and situations.

I generally had no problem without modifier in my Off Road Auburns but they would get pretty noisy on low speed turns in the paddock.