Hey guys I need some suggestions about which oil viscosity is best for my SBC 350. It has a hyd flat tappet comp 270 magnum cam. I will be using VALVOLINE VR-1 RACING MOTOR OIL because of the extra additives for flat tappet cams. Should I use 10w-30 or 20w-50 weight? I live in Southern California so the temps are pretty warm here, even during the winter.