Our 3800 currently has one quart of Trop Artic 10w30, one quart of Maxlife 5w30, two quarts of All Climate 5w30 and a half quart of Rislone for good measure. Hey, you asked!! I'd recommend sale of the week 5w30 for the harsh Wisconsin winters. No sense putting synthetic in a 500 dollar car IMO.
Keep an eye on the coolent; the 3800 by other people's word is a reliable plant but it to suffers intake gasket leaks and warpage of the plastic upper manifold at the EGR port. Your's might be old enough to have a metal upper intake though.