I plan on doing it when I install a Montune radiator, but if that does not happen soon, I will use one of the better dealer's coupons for like 30% off of this service, and have it fully flushed out, and new yellow Motorcraft put into the system.
I have ~5 years, but only about 32K miles on the factory orange stuff.
But by changing the concentration twice a year for summer and winter seasons, and using new orange coolant every time for the winter change, it is almost as if I have changed it out multiple times already (but yes, of course that is not like a full flush out, which gets all of the sediment, corrosion deposits, and other particles/solids out of the whole system).