differential oil, hellllllp!

Hi, im changing my differential oil in my car, it has limited slip, first one ive change so idk but i bought valvoline synthetic gear oil, it says its for limited slip.... but does this mean i still need the additive for it? or is it good to go just the way it is? please help, thanks!

Depends on which diff you have...my Auburn (clutch type) hates synthetic...noisy as hell if I use it. So I stick with regular mineral based oil and 14 oz of addidtive. Nice and quiet.