Quote Originally Posted by JAMAS View Post
I am not a pro, but I believe coolant does loose its effectiveness overtime. A flush and refill every so often is a good thing.
I don't think that is correct.

The major constituent of most coolants is some form of glycol, although there are other chemicals used. It does not break down chemically in a sealed cooling system, it will breakdown in the environment.

What does break down are various additives that inhibit corrosion. It also gets dirty.