I run Amsoil 100% Synthetic 5W-30 Motor Oil in my Trans Am 305 H Engine. Best Oil I have ever used. I have tried them all, from Mobil One to Royal Purple and Red Line.
I even had Oil Specifically Blended for my Trans Am. Based on Climate, Storage ect, at
http://www.bndautomotive.com, not cheap, but still feel the Amsoil runs better in my TA
About $9.00 a quart. If you buy by the case, you may do better, depending on the parts store.
Car runs awesome with it. I use it my everyday car as well.
Also run Amsoil Gear Oil in the Rear End.
Hope this helps