 Now, first of all, how do you know when things are going bad? If you're getting your car serviced, your technician should be looking at that cooling system. It's good to get that coolant flushed every 30,000 to 40,000. Every car manufacturer recommends something different. But over time, antifreeze will break down, and it'll start to get brown, or it just doesn't perform like it should. So it's best to keep that cooling system serviced. Mm-hmm.