Always follow your manufacturer’s recommendations as outlined in the owner’s manual. Typically, the cooling system should be flushed out at least once every two years or 30,000 miles. The best time is to have this service performed is in the spring or fall. A flush should never be done as a repair for an overheating problem. A coolant flush after the repair is recommended to clean the entire system and replace it with the proper anti-foaming agents, rust inhibitors, and water pump lubricants.