Due to government regulations, in recent years oil manufacturers have removed the zinc and many of the other additives from their motor oil. However, using an "off-the-shelf" brand of oil during the critical break-in process can lead to a failure. Thus, COMP Cams Engine Break-In Oil Additive is designed to extend the durability of internal engine components including camshafts, valve train components and all moving parts in your new or rebuilt engine. It does so by using a special blend of extreme pressure additives no longer available in "off-the-shelf" motor oils. COMP Cams Engine Break-In Oil provides added protection during the break-in process and is compatible with any petroleum, synthetic or blended motor oil.