I am pretty sure there are no production flat tappet engines out there, they stopped using flat tappets around 1989, because they were ruining catalytic converters with the zinc in the oil, and they kept ruining cams without the phosphorous in the oil, so they just simply went to roller cams, which eliminated both problems. You may or may not need break in oil, GM engine assembly lube is the magic goo that constitutes the difference between "regular oil" and "break-in oil" they use about 6 ounces assembling an engine, which coincidentally is about what is in one of those little containers of zinc additive. But since I don't know exactly what the requirements are for any particular cam, what the actual components that are in the assembly lube being used, and the actual level of any additive in the oil that may or not be used. Not to mention the difference in price between the two is about $20 for an engines worth. And for the amount of money that gets spent on these engines is entirely worth the extra $20 of insurance in my opinion. It is most decidedly worth it in the amount of work it takes to replace a cam. You can do what ever you want, I will use a designated breakin oil. The ZDDP additive may cost a little bit, but nowhere near as much one of those "smart phones", or a boat, or a set of golf clubs. Or what ever someone thinks they "NEED" If $20 is going to break you, you are in the wrong hobby.
