Modern motor oils have changed and no longer include the Zinc or ZDDP, and extreme pressure additives that are needed to protect the camshaft and lifters with flat tappet cams. The 4 ounce bottle treats 5-7 quarts of oil and prevents scuffing, galling & provides protection for the valve-train on your muscle car, hot rod, street rod, or classic car. Compatible with synthetic, petroleum, and blended motor oils. Add a bottle to the crankcase of your engine at each oil change.