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 Perfomance describes his positive experience testing Lucas High Zinc Engine Break-In Oil
After having used and tested Lucas Oil Products for the last Six years, with excellent results, when Lucas introduced their new Engine Break in Oil we where anxious to try it. We were especially hoping it would offer some insurance for flat tappet camshaft break in. After adding Lucas Break in Oil and Break in Additive to our existing Lucas inventory I’m happy to say we have not had any camshaft failures. With the added protection and power of Lucas products I’m confident we have given our customers the best.