Engine assembly lube
Many, many years ago when I worked for GMC Truck & Coach, GM had their own assembly lube that came with their cams. I have used STP and many other products including good old 30 weight, when building engines. I never had any problems with any of them. When I installed the Comp Cam in my Barracuda, I used their cam lube. I never used grease. Grease is grease, not engine lube. grease will melt at normal engine temps and, like has been already mentioned, will collect at the bottom of the pan and collect any dirt that possibly could somehow enter the engine.