The fogging is mostly for the lower end bearings, crank, rods,etc., which may end up with insufficient oil on surfaces during lay-ups to prevent corrosion...if motor has oil injection then fogging may be more important due to very thin oil/fuel ratios at lower RPM's right before shut down...pre-mix maybe not so critical since oil/fuel ratio is set at all RPM's....If you're operating in a saltwater environment then fogging is more important....roll the dice with preventive maintenance but with the price of outboards maybe best to fog.....