There are a few ways that you can drain coolant without making a mess. The first way is to use a funnel. Funnels are great for catching any drips or spills and make it easy to pour the coolant into a container. Another way to drain coolant without making a mess is to use a clean, empty milk jug. Simply place the milk jug under the radiator cap and open the valve. The coolant will flow into the jug and can be poured out later with no mess. Finally, one of the easiest ways to drain coolant without making a mess is to use an old towel or piece of cloth. Simply place the towel under the radiator cap and open the valve. The coolant will flow onto the towel and can be easily disposed of.