i hear thousands of stories about GM differential additive, some good and some bad, i need some opinions, do i add fluid when i change my oil or not?????????

 

if your manual says to use it, use it.

 

i was told by someone on this board that if it says "synthetic fluid for limited slip", then you should be ok without the addative. So thats what I did, Its been about 7k miles since I changed the oil. Haven't had any problems that I know of.

 

Not all synthetics have the additive, it is only in there if it says it is. Some lubes just aren't limited slip friendly thats why some note for limited slip.