Waterless coolants are very simple; they contain no water. They are glycol-based with additives to meet specific requirements. The claim is that corrosion does not occur as rapidly without water, and without water vapor, the system is under less pressure. However, waterless coolants run at a significantly higher temperature, and while it will not “boil-over,” it will overheat an engine and could lead to significant damage. Additionally, should you lose some coolant in your system, you cannot add water to make up the difference.