you need to buy a coolant additive from either the ford dealer or john deere or IH.. its for the radiator and its a coating that prevents cavitation.
Good news.. its cheap and a bottle of it will treat two radiators. So... once every 4 or 5 years.. flush it, and add new coolant, new antifreeze and the coolant treatment.
And your good. be it a john deere or ford or kabota or what ever..