[Rod]

The coolant (50-50 anti-freeze and water) needs to be flushed out and replaced.

Any advice on how to do it??

I have Crusader gas engines with heat exchangers.

[Uhehner]

My college chemistry professor said "antifreeze never goes bad, only the rust inhibitor wears out". In my 50 years of boat and car ownership I have never replaced antifreeze, just added rust inhibitor once a year. And I keep boats and cars over 10 years and never had a problem. I buy it in the autoparts store, looks like milk.

Capt. George