In both my 3100 '94 Grand Am (now past 200K miles) and my 3800 '04 Monte Carlo (and the rest of my fleet), I use conventional (Quaker State, Havoline, Valvoline, Castrol) and change 3000-5000 miles. I prefer a Bosch filter but I sometimes go for a Fram.
So far, I feel this oil change regiment has served me well. So, I am hard pressed to switch it.