Red Line new Engine Oil Break-In Additive (Part #81403, MSRP $12.95) provides conventional motor oils with antiwear additives like zinc and phosphorus (ZDDP) necessary to protect against camshaft and valvetrain damage on break-in.
This is especially important in flat-tappet engines where bigger camshafts grinds and higher valve spring pressures are now popular. This additive is designed to allow pistons rings to seat properly, while allowing other engines components to avoid excessive wear.
A 16oz bottle treats up to 12 quarts of motor oil, so in many cases one bottle can serve two different engines. This product can also be used in conventional and synthetic oils during regular operation, providing an extra package of protection otherwise not found in most motor oils.