Whatever oil you do use, I think it's important to change it before you put it away for the summer. Or at least run it a while in a warm dry area to evaporate any water from the oil. My experience is that these things tend to get a lot of water in the oil from inhaling snow. I always see ice on my dipstick. Many of them, including my Troy Bilt, don't even have air filters if you can believe it. It's probably true that there's no dust in the winter, but I think they would have problems with the air filters getting wet from snow if they did have them, so they leave them off.