How many miles are on this car?
Was the coolant & flush on schedule for change?
Was this car using orange or green coolant?
Whats the normal life of a DCCV?
The age of coolant might be more of an issue, than mileage.
I would consider a flush with old parts, a new DCCV, water pump, and thermostat.
A good premium green coolant, might have a better rust protection aginst mix metals.
50/50 mix by the gallon is better, than using 50% tap water!