Oh boy, you're opening a can of worms. It's easier (I don't know if cheaper) to get oil with high zinc. I used Valvoline VR1 Racing Oil upon the recommendation of a local Mopar engine builder who I trust. It's available at all my local auto parts stores. And, you'll find a lot of people with flat tappet/non roller cams use it and recommend it. If you decide to go with additive instead, the additive will tell on label how much to use. Good luck.