Got to know what cam is in the engine...Flat tappet cams must have zinc in the oil--Joe Gibbs, Brad Penn are probably the best of these. However roller cams thrive on the reduced friction of synthetics--my personal favorite is still Mobil 1 racing, 10W50. The Ford semi-synthetic is also very good oil for roller cammed engines, I've run that in a few because it's reasonably priced and available at Ford dealers and most parts stores....