Maximum protection is essential when pushing your engine to the limit. Operating at high engine output and high temperatures or alternating between periods of high RPM's and throttling down to low RPM's or idle puts serious pressure on engine oil. Mercury Racing Four Stroke oil will not break down under these conditions. It maintains its viscosity, protects against varnish buildup and sludge formation and exceeds the rust protection requirements for NMMA certification. Do not use in any two-cycle engines. Verado outboards prior to 2007 must use 25w-50 racing oil. Verado outboards 2007 and newer can use 25w-40 synthetic blend 8M0078630.