Maxima Oil SEMI-SYN racing oil is a complex blend of synthetic esters and highly refined petroleum base stocks, offering protection beyond conventional oils. Technologically advanced additives containing special anti-wear/extreme-pressure features protect critical engine components from punishing loads and peak temperatures generated by high performance engines. Advanced, shear-stable polymers resist mechanical breakdown and viscosity loss of the oil. SEMI-SYN delivers increased horsepower, optimum engine cleanliness, reduces wear on bearings, cams, lifters, and crankshafts—and extends engine life. The high zinc/phosphorous formula is engineered for use in flat tappet and roller element engines. Select the oil weight recommended for your application.