Royal Purple combines highly refined mineral oil, preferred for engine break-in, with advanced additives containing high levels of zinc and phosphorus to optimize protection in the flat tappet and roller engines. Royal Purple Break-in Oil is formulated to allow optimal ring seal and protect rotating assembly components such as the camshaft and valve train from initial start-up wear. Its high film strength provides engine protection superior to full synthetic oils that are not engineered specifically for new engines. Perfect for your new factory-ordered vehicle and engine rebuilds, Royal Purple Break-In Oil is fully formulated and does not require the use of any other chemical additives. After the engine is broken in, switch to a high performance engine oil for your vehicle.