Here is my system for winter:
- I change oil in the four strokes, just don't like the idea of old motor oil sitting still in there for 4 months.
- Add Stabil to tanks, run engines to get stabilized fuel into carbs.
- Top off tanks with stabilized fuel.
- Charge batteries periodically over the winter.
- Start engines once or twice mid winter, maybe.
Quick and easy, but in ten years, never a problem with seven 4-strokes and maybe twelve 2-strokes in the garage.