I like to use the Joe Gibbs Racing oil "BR" oil for break in of new engines that use flat tappet cams. The Joe Gibbs guys told me to run it for 300-500 miles and then switch over to a conventional race oil. The "BR" oil is basically a 30 WT oil and it has ALOT of zinc and other additives for critical component protection in new engines. Ive never had a problem with cams going flat using this stuff. The Joe Gibbs guys told me to use it on the piston rings and cylinder walls also. I tried it on one of my own engines and it doesnt smoke and it tests great on the leak down test.