Failed Radiator

Can I put a different antifreeze in the radiator beside the orange stuff?

yes but the system has to flushed completely b4 you use a diff coolant. if not it will cause major damage to mix coolants. i rec you stay with dex but change every 30 to 40k miles

I bought the truck with 30,000 miles and in 3 years put 20,000 more miles on but never changed the coolant. There was no indication that I could see that it need to be changed and the places I took to have work done never said the anti freeze was bad.

well maybe you need a new mech.