In most cases, a vehicle's coolant should be changed roughly every 24,000 to 36,000 miles. A driver may want to change his coolant more if he often drives in hot temperatures.
Before changing the coolant, a driver should also consider flushing the radiator. Doing so not only cleans out the old engine coolant, but also gets rid of any grime and dirt that might be in the radiator. The vehicle's owner's manual usually lists how often the radiator should be flushed. The driver can choose to flush the radiator himself or have a professional mechanic do the job for him.