The "PLUS" is for the extra additives above and beyond the normal additive package found in ordinary racing oils. This true high performance lubricant was especially developed to protect top fuel engines.
Big power also means higher cylinder pressure and increased load on critical engine components. The key to preventing dangerous metal-to-metal wear often comes down to viscosity.
Steve Brule from Westech Performance describes his positive experience testing Lucas High Zinc Engine Break-In Oil