Coolant Flush?

I suggest you read your owner's manual and do what it says unless you have some reason to believe it needs to be done sooner than the recommended service interval. If so, do it.

Automotive Coolant Test Strips

Determines an engine's protection against freeze-up, boil over and acid corrosion.

This is the best way to find out if you need a flush job any time and acid corrosion is the worst and never seems to be checked. Check out the Penray Products web site this is what our Parts Plus store sells the garages(top notch products )