I've got an 85 gallon tank so it's tempting to tap the cheap gas prices and fill 'er up. I talked to the folks at Monahans and was told if you've got a plastic tank leave it empty as possible. Aluminum might get some corrosion if you leave it low all winter but if you fill it the octane loss may be an issue and you could be sputtering for the first few trips, not so great for the engine.
I've got 10 gallons left with a double shot of the Johnson 4+2 treatment which I run all season at the recommended mix.
Fogged it yesterday. Don't forget to grease all the zerks to push out any water. I also spray the CRC version of wd-40 all over the engine and grease any exposed moving parts. Wipe down the greased parts in the Spring and there should be no corrosion. Drain and refill the lower unit gear oil, no milk this year so my seal job is holding up well. Probably time for a water pump job but I think that will have to wait until Spring.