Best High Zinc Oil
I've been breaking in my engines with either conventional old race oil or conventional 15w-40 diesel oil with Comp Cams zinc additive. Amsoil now has a special break-in oil now which I have yet to try. After break-in I run the engine on Amsoil's 5w-20 Dominator race oil. The also have other viscosities in that series. But for street and high performance use, they have a wide variety of other high zinc oil to choose from as well.
[ame]http://www.amsoil.com/techservicesbulletin/MotorOil/TSB%20MO-2007-08-08%20Flat%20Tappet.pdf[/ame]