For a Mercury two-stroke model, 2- to 20-horsepower outboard motor manufactured before 1980, use a blend of unleaded gasoline with a posted octane minimum of 91 and Mercury or Quicksilver Premium Plus 2-Cycle TC-W3 Outboard Oil at a ration of 50 parts fuel to one part oil. If the motor is over 30 horsepower, then use premium unleaded gasoline with a posted octane minimum of 95 instead.
For Mercury Verduro models that are between 275 and 300 horsepower, use premium unleaded gasoline with a posted octane minimum of 95 along with Mercury or Quicksilver OptiMax/DFI 2-Stroke Outboard Oil. For Mercury 350 horsepower Verduro models, use premium unleaded gasoline with a minimum of 98 octane instead of 95.
Mercury Verduro model motors contain an additional oil tank contained within the body of the boat. Fuel and oil for Verduro models do not need to be pre-mixed as the separate oil reservoir that is characteristic of these models automatically blends the oil with the fuel at a ratio of 50 to 1. Comparatively, the oil for the two-stroke models of Mercury motors must be added while the fuel tank is being filled with either the unleaded or premium unleaded gasoline, depending on the horsepower.