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 Break-In Oil is formulated to provide the critical wear protection needed by the engine valve train and camshaft while allowing new piston rings to quickly seat to the engine cylinder walls. Break-In Oil combines highly refined mineral oil (preferred for engine break-in) with an advanced additive package containing elevated levels of zinc/phosphorus anti-wear additive to optimize wear protection during the sensitive engine break-in phase. Royal Purple Break-in Oil is a fully formulated conventional 10W-30 engine oil and does not require the use of any other chemical additives. 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 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.