The process of preparing engines that use ethanol blended fuels (e10 and higher ethanol blends) for colder temperatures. Some care is required, particularly for boats? and other marine equipment. A standard process for "winterizing" equipment has been defined by the Renewable Fuels Association (RFA.)

"Seasonal changes in the ambient temperature can cause the freezing water or condensation to build-up inside the engine and fuel tank. Proper storage preparation is essential for keeping your marine motor trouble free and running smoothly.The addition of ethanol does not shorten the shelf life or stability of
motor fuel nor does it affect the fuels combustibility. All fuels, gasoline and E10, are susceptible to degradation? such as the introduction of water or dirt that can cause the fuel to weather, leading to hard/ poor start conditions or ultimately causing engine damage...." Read Full e10 Winterization Guidelines From The RFA.