Winterizing 350 Mag boat engine

I have a Searay boat w/ 350 Mag engine and fuel injection. A friend says that it is desirable to spray an engine fogging oil in the intake manifold until the engine cuts out to winterize the engine properly. I have been winterizing my boat for a couple of years without this. Anyone have any comments or advise.

There are 2 schools of thought on that. Spray into air intake until it dies or fog cylinders after it is off. I have a 2 cycle and spray the air intake until stall was recommended to me by my great boat mechanic. His rationale was that process protected many more parts than just the cylinders. I don’t know how you would spray fogging oil into the intake manifold. Had a 67 15’ searay with 100 hp evinrude until I got tired of fixing it.

Where will the boat be stored? If covered it shouldn’t make any difference.

I have “fogged” carb’d motors but not any with fuel injection. I have some concerns about the affect of the fogging oil on the injectors and other parts of the fuel injection system. Don’t do it until you check with a marine mechanic.

The real issues in winterizing is to be sure all the water is either out of the block, or has antifreeze mixed in it so nothing freezes. If you really want oil in the cylinders you can pull the spark plugs, shoot some oil in the cylinders, crank the engine just a couple of rotations and replace the plugs.

Oil in the plug holes would seem to be the best insurance against moisture problems in the cylinders. Fogging on a crankcase charged 2-stroke is much more critical with respect to the bottom end needle bearings, etc.