i think it be a good idea to turn over the engines half way through the winter too. just a revolution or two. keep the rings from sticking. which is the main reason for fogging a motor in the first place. spark plugs should be changed in the spring after fogging anyway. not sure why you cant fog an efi engine though. interested in seeing someone post why.

It's in the Mercury books/manuals. It cakes on and can mess up the IAF/MAF sensors.

Merc recommendation is:
1) Dump 1/2 of fuel water separator out and fill with 2-stroke oil, re-install and winterize with this mixture.
OR
2) Run fuel line to fuel pump from small can of gasoline with 2-stroke oil premixed. (Look in the book for the ratio.)

It's discussed on here every year.

On the carb motors I have used ATF for years poor it right down the carb till it smokes out the exhaust

There was an article in Teague on tech a couple of years ago. He reccomended that you used a garden sprayer with mavel mystery oil for the 525efi, 600/700 sci ect.

Been do'n it like that the last few years in my 525's, no probs!!!I just put new filters on at winterization w/ the oil poured in!

I prefer to put the 2-stroke oil in the 1-season-old fuel/water separator (after close inspection for rust); and put new fuel/water separators on in the spring. I've had great luck with this method for going on 10 years.

First time this year, I winterized with a portable tank of non-ethanol fuel as well. I still have stabilized ethanol laced fuel in the tanks, but I'm going to pump that out into my daily driver over the winter.

Well, I beg to differ with Mercury on that.
IAT sensors can be cleaned with a shot of brake clean in about 5 minutes if necessary and there is NO (MAF) Mass Air Flow sensor on any Merc efi and chances of actually getting any foggin oil into the (MAP) Manifold Air Presure sensor are pretty dang remote. Better chance of gumming up the injectors with oil doing it Mercurys way IMHO and that comes from being in the auto business and servicing efi systems for almost 30 yrs now.

that's what i was thinking, based on my 20 year auto experience...

Pantera was 6 years and 275 hrs. Isn't that long enough?????
The AT has had 3 seasons and 150hrs and is not going anywhere soon.

I also use my boats often enough that keeping the cylinders coated with oil isn't an issue.......unlike some trailer queens

Don't shoot the messenger guys. This has all been discussed here in the past.