94 firebird formula posi rear-end doesn't bite all the time.?

[B 456]

sometimes the left tire doesn't spin with the right,i changed the oil with a semi-synthetic Valvolinene oil.what is the right oil for rear-end.and when the car gets sliding sideways doing a burnout the rearend kind of makes chatteringing sound.

 

[Zimgxp]

You need a bottle of lsd suppliment. You can get this from the dealer.