Yankees1,
I've been using Amsoil for almost 25 years, but if you are dead set on changing oil every 3000 miles, I'd run Mobil 1, 5w30. I prefer the 5w30 over the 10w30 for an over head cam engine, as it is important to get sufficient oil flow while the engine is warming up. Actually, I'd run the Amsoil 0w30 in this motor, with a 7500 mile change interval if I drove it really hard.
I am close to buying a 1994 Porsche 911 Targa, w/ Tiptronic for my wife and will probably run the Amsoil, Series 2000, 0w30 in that motor in the winter, and the Amsoil 10w-40 in the summer. This 3.6L motor has a dry sump and holds about 10 quarts of synthetic - they all come with Mobil 1 right from the factory ....Not as fast as a Vette, but the handling is incredible, if you don't mind hanging the tail out and never lifting or braking in the middle of a turn ....The brakes are amazing as well - it feels like a giant hand has reached down and grabbed the car.
TS