The Dexcool was really keeping down corrosion and deposits in my 2003. I'm not sure if the coolant was ever changed until I did it at 200,000 km. And it's readily available and inexpensive. I see no advantage to going to G48.
But if you insist, drain your current system and see what it looks like, including the thermostat. If it looks fine, refill with Dexcool. If you don't like what you see, do a thorough flush with water (remembering the heater shut-off valve if your car has one), and then refill with what you like.
But if you insist, drain your current system and see what it looks like, including the thermostat. If it looks fine, refill with Dexcool. If you don't like what you see, do a thorough flush with water (remembering the heater shut-off valve if your car has one), and then refill with what you like.