The "PLUS" is for an extra additive package above and beyond a normal 20w-50 racing oil.
Lucas Petroleum Motor Oils are formulated with the highest quality paraffinic base stocks and an exclusive high performance additive system, including lubricity and anti-seize agents.
Lucas Synthetic High Performance Motor Oil is an excellent product that provides the consistent viscosity needed for precision ET racing.
My son and i use lucas oil in our racing lawn mowers and we have great results from it.