What kind of coolant do I use in a 2007 Chevrolet Cobalt?
50 / 50 anti freeze to water is the old standard. Check the owner's manual or the antifreeze container. In Northern States in the winter time the proportions will change due to the VERY COLD weather. In the Southern states, it may remain the same. Antifreeze helps prevent rust and crud from forming also. It is a lubricant in a way and keeps the coolant from overheating quickly.
And... your car came equipped with GM's Dexcool. Use only Dexcool and water in your system. You cannot mix other types of antifreeze with it. Apparently it will clog the system. Read the labels carefully to make sure you have the right one.
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