Hi all, We store over 500 boats here in Ohio inside heated, inside cold and outside storage. ALL fuel has at least 10% ethanol in it. I store all my boats around 1/2 full. This is contrary to old thinking however old thinking didn't involve ethanol. Ethanol breaks down directly into water in about 2 weeks. Use a good stabalizer, "Startron" is the best I have found. Also (as the diesel guys have known for years) fuel filtration is very important. You MUST have good water seperaters.