Generally, break in oil is very low on detergents, which counteract the chemical bonding of the ZDDP and other anti-wear additives. You also have to consider you need the piston rings and cylinder walls to mate to each other. I have no idea how mixing chemicals together in your crankcase are going to affect your cam and your rings. I'd stick with specific break in oil. My Lunati cam came with Joe Gibbs Racing Driven cam lube, so I just got some of their break in oil from Summit, along with their Hot Rod oil which is designed for old cars with flat tappet cams that may sit a long time, like through the winter, without running.