COMP Cams 1590-12 12 Quarts of 10W-30 Break-In Engine Oil - High Performance Motor Oil for New Engine Break-In & Rebuilds - Ideal for Muscle Cars, Hot Rods & Performance Vehicles

I use for break in and regular fill ups both! Has critical additive in oil zddp! I have now used for a few years with no issues. Comp Cams says that this oil is to be used not for just break in but also for regular use since the cam needs the extra zddp for the life of the engine. I love this product and it's price is great even though there are about 5 products out there that are equal, the prices are not. If this oil is out of stock, then try Valvoline VR1 racing oil, Royal Purple, Lucas Oil Hot Rod oil or Racing Oil, Mobile 1 Racing Oil, AMSOIL Z-ROD Synthetic Motor Oil, and Brad Penn oil. BUT ALWAYS USE BREAK IN OIL ADDITIVE WHEN DOING INITIAL BREAK IN!!!