No fuel additive will protect the expensive bearings that the bottom end of most higher output two strokes have.
If stored indoors in a relatively secure building it may not be necessary at all.
If you use a high end oil it is also rarely needed. My Amsoil 2 stroke oil has additives specifically to prevent damage when stored.
If stored outside then fogging is cheap insurance...
The literature says that it coats all parts of the fuel system in corrosion preventing vapor. If I'm running this stuff, is it necessary to fog a motor?
What that means is it will protect the fuel system like the injectors and carb from corrosion.Fogging and stablizing the fuel are 2 dirrent things.... Fogging the motor with some kind of lube depending on if its a 2 stroke or 4 stroke that will lube all the internal parts of the motor like the cylinder walls etc to prevent a dry start in the spring... If you store in a cold garage or outside It would not be a bad idea to fog it but if its inside and heated I would not fog it just run some fuel stablizer threw it.
Two cycle outboards typically have exposed needle/roller bearings everywhere -- on the crank supports and both ends of the rod. There is lots of exposed surface area. This is unlike automotive sleeve bearings which can remain pretty much sealed for years after running.
Storage protection requires a sticky oil that drives off and continues to excludes moisture, even in the presence of a little fuel and salt crystals. You need a heavy fog of oil droplets to do that, not a thin residue from a fuel additive that needs to be formulated to not clog a carb.
I think too much is made out of the whole fogging process. I have bought many two strokes in "Poor" condition, that set for years and it took little to fire them up. The carbs are much more problems than the cylinder/crank/internals. I have never seen a two stroke lock up from sitting, even outside. The needle bearings are very durable and so are the two stroke engines. Its a make you feel good and may ease your mind. I like sea foam and let things sit for years and they seem to fire right up. I never had luck with Stabil, but I go longer than a month.
No offense, but we see a ton of corrosion issues here with salt water and persistent high humidity.
Trust me on this, when your expensive outboard or jet ski has the TINIEST fleck of rust on a big end bearing it gets ugly very quickly.
The lucky fact that you have never experienced it does not lessen the risk nor is it any reason to ignore it...
I am in sunny Florida and have bought a lot of beach rental atv's and know your not kidding on what salt water will do. Ive seen it totally rot the frames out. I can only imagine what a jet ski gets put through engine wise. Salt water should not make it in the engine. I would think the oil wash would be a constant fogging process. I guess Ive been lucky. Almost all the atv's I bought came from humid happy Florida and I have had 0 problems with crank bearings.