What does the owners manual say?
Dexcool, when it first came out was blamed for a lot of cooling system failures. People thought it would be good for 150,000 miles. They forgot about the 5 year part entirely. Time is more important than miles when it comes to coolant, particularly when all aluminum engines are involved.
The only thing that puzzles me is the 2018 Mercedes that I have. There is no recommended coolant changes out to about 10 or 12 years! (forget exactly which right now) No mileage limit involved. No mention of coolant change on the maintenance chart either, which goes past 110,000 miles.
Strange to me.