I've been using Amsoil (Service spec SJ-CF) in all my vehicles for years. Used oil analysis shows it works well in my late model cars and even in my girlfriends 05 Camry.
A number of well respected engine builders (read NASCAR) are suggesting Rotella 15W40 in early model muscle cars. Yep, diesel oil.
A excellent website on this topic is:
www.bobistheoilguy.com. Good info there that all of us 'gear heads' can use.