I use Delvac 1 5w-40.....but it is pretty cold up here. Rotella makes a sythetic that is pretty good and reasonably priced. I have heard good things about the amsoil stuff too. It kinda depends on how much you want to spend and if you are going to extended oil drain intervals by using oil analysis.
I have used 10qts of Valvoline 15-40. I looked into synthetic but heard its bad to mix the two and you obviously can't get ALL the oil out of the motor. On the same level synthetic is sometimes hard to find. If im out and need to add a little and cant find it
I use AcDelco filters as well on all my vehicales. Every auto rep I ever talk to swears by it.
I planned to use synthetic in my truck until I tried to find it. I went to the post exchange and they had no oil petroleum or synthetic based meeting the CI-4 or CH-4 rating for diesel engines so I went to two auto parts stores and none their either, so I checked Wal-Mart and they had 3 petroleum based brands but no synthetic. So I guess I won’t be using synthetic for awhile I don't feel like driving all over to not find any. Maybe I need to let my fingers do the walking. But about your question I would only use it if you plan on extending your oil change interval. If you plan to keep the same interval you are just wasting money and getting no benefit from purchasing synthetic.