I have a 1981 280zx turbo with 28k miles on it. I just replaced the original turbo with a rebuilt unit including new turbo gaskets and oil hose. I have also replaced the oil pan gasket, valve cover gasket and oil pump. The oil pan was clean, no sludge whatsoever after 40 years. My question is what oil should I use? I'm leaning towards Valvoline VR-1 synthetic 10W-30 because of the high zinc and phosphorous and it's a flat tappet cam. Or, should I be looking at M1 or PP and use a ZDDP additive? Keep in mind this is a hot air turbo and not water cooled.