Originally Posted By: RocketUSA
Is there a recommended ZDDP level for flat tappet motors though?
Yes, the actual number is 1200PPM.
However, as you might expect, there are many other factors. Including the viscosity of the oil, it's change interval, it's base stock, other additives, and so on.
Generally speaking, a straight dino 10w oil, with 1200PPM ZDDP won't protect your flat tappet camshaft well enough, especially in tough conditions. Where as a fully synthetic, Mobil 1, 15W-50 with 1100 PPM will provide plenty.
If it were my engine, I'd use M1 high mileage 10W-40, or M1 15W-50. Both will flow well when cold, and provide excellent lubrication of flat tappet cams.