What gear oil for new posi diff

[G NASTY]

I have a new eaton 30spline posi going in, I heard synthetic is not recommended. Is there a preferred diff oil? Or Additive?

 

[charlief1]

I'm using Lucas with the additive seperate if it helps.

 

[2QUICK2B6]

valvoline here with the GM posi aditive going on 5 yrs and countless pass's and about 10k road miles