zinc or not?

Hey Dave I have been wondering the same thing...to zinc or not to zinc. When we did the engine last year of course the oil used to coat the cam during the rebiuld has the zinc in it, and some of the guys my dad has talked to say that should be enough unless you plan on racing that car often with high RPMs. I always used Penzoil on my 273 for years without a problem, and the 340 seems to be purring fine for the last two years since it replaced the 273. These guys from Piston ring and other mechanic shops whom my dad has known for years think it is not necessary....but I am still wondering.