Reply to "Squealing noise when turning"

I think I know what it is now. This is a common problem on rear axles with LSD (limited slip diff) when using the wrong type of oil. It can be solved by using an oil with LS additive to get the friction at the diff right, but for the Pantera that has a transaxle it can be problem with shifting when using LS oil.

I found this conversation on the internet that explains it:

Dave
Thanks for your answer. I don't understand why you recommend the 75W90NS instead of the regular 75W90 gear oil.Your net site has the following statement:
"75W90NS - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140"
Can you help me understand why you have advised the opposite to this?

I recommend the 75W90NS in the Pantera because the gear lube is being used to lubricate both the transmission and the differential. The NS fluid doesn't have friction modifiers so isn't too slippery for the synchros and will allow good shiftability. The note that you sent and underlined is specifically relating to rear differentials, not transaxles. If the transaxle uses a clutch type limited slip and excess chatter occurs when making a slow tight turn, then a slight amount of friction modifier could be added to the NS to reduce this, being aware that too much can effect the shiftability. The 75W90 contains 5% friction modifier and this could be too much for some synchros.

Regards, Dave
Red Line Oil