What differential oil do you use?

I have a 07 automatic coupe and im doing a differential change since im not sure when the last time its had one since ive got it. Ive been doing some searching and i see alot of people using 75w90 instead of 80w90. Also does the automatic need limited slip additive ? Locally here there is no 80w90 with slip but i found 75w90 limited slip from valvoline. So im thinking i should opt to use that. Thoughts ?