A coolant flush should be done about every 50,000 miles on a standard semi-truck. Not doing this service can cause radiator contamination, overheating, and corrosion or rust build-up. Doing this will prevent electrolysis from pitting liners. The reason we do coolant flushes is to renew the fluid in the radiator and keep it contaminate free. In the winter, coolant protects the engine from freezing over while in the summer the coolant keeps the engine from overheating. An overheating engine can cause many problems which is what makes this a necessary maintenance item. If you have neglected to do a coolant flush or are entering the recommended time interval to get a coolant flush done, schedule your appointment as soon as possible.