If you truck is late 99 or newer use the ELC which is what some are calling Red coolant. It is vastly superior to any of the others and Gold is not good for our trucks IMO.
With the ELC you no longer have to ever add any SCA additives period. In fact doing so will bring you down to having to change it out like a "green" coolant. They are good for around 7 years 300K miles IIRC. Some vary a bit but the point is a very long time LOL
Change it every 5 years would certainly keep you safe.
Do your water pumps a favor and get a bypass filter or when the pump goes get a IH version with built in filter port. You would not believe the amount of left over sand form the block casting that left in some of these. Some filters are full of sand after just a week. That's why a good practice is to cut open the first one after a week and then decide how long to run the next based on what you find until it starts coming out clean. Then go to SCI