The engine bearings, camshaft, lifters, pushrods, and rocker arms are parts that we need to lubricate for proper break in. As the engine turns, the lifter spins on the cam lobe. Without proper lubrication it will ruin the cam and the lifter. Flat Tappet lifters have seen this become an issue with Zinc being removed from modern oils. Roller lifters break-in procedures are similar but don’t have an issue with modern oils..