Usually change the gear oil in the lower unit, if the motor will be stored outside it prevents any water in the lower unit from freezing. Do it anyway, verify the old oil is not contaminated with water(bad seal)(remove prop, check for monofiliment line that can ruin prop seal)
While running, spray fogging oil into the carbs through the air intakes till the motor stalls, this lubricates the cylinders and crankcase for storage.
If not draining all fuel, add fuel stabilizer while running to ensure it gets into the engine.