You should change coolant in every 30,000 miles. For new car, change the coolant/antifreeze after the first 60,000 miles, then every 30,000 miles. However, the coolant change suggestion varies from vehicle to vehicle. Some models recommend that it not be changed for up to 120,000 miles. Many service companies recommend doing it more frequently than the maintenance schedule suggests, such as every 30,000 or 50,000 miles. Because environmental regulations have pressed automakers to limit the number of waste fluids disposal, current cars feature longer intervals between fluid replacements of all types. Here's my go to refiller kit.