Summary of old posts:
1) With current spec car oil (about 600 PPM) you will likley have problems with a flat tappet
2) Diesel engine oil (about 1300 PPM) has about 2x the zinc and phosporous of car oil. Probably OK as purchased for mild well broken in engine.
3) Adding STP helps supplement zinc but doesn't have enough to correct car oil. Diesel oil plus STP is what I'm running.
4) Valvoline and some other companies have racing oils with high zinc labeled "for off road use only" but may be hard to find.
5) Dedicated motorcycle oils have high zinc.
