Engine builders have grown increasingly concerned that current engine oils that are API licensed for new cars and trucks do not provide adequate wear protection for freshly built performance engines, particularly those using flat tappet camshafts and lifters. Royal Purple has addressed this issue with Royal Purple Break-In Oil.Royal Purple recommends switching to a high-performance synthetic Royal Purple engine oil after break-in for maximum engine performance and protection. We recommend using our Royal Purple Engine Break-In Oil for a minimum of 500-1,000 miles in street driven gasoline engines to assure that the complete ring break-in has been completed before switching to one of our full synthetic engine oils. If need be, you can use for up to 2500 miles.