28 years ago I bought a new Chevy Blazer. To date, I have never changed the radiator and did however change the AF 16 years ago. The Blazer has a new body, mostly, on it and about 150K miles. So when should I change the acid/caustic AF along with the radiator? I am confused as this truck runs perfectly as it was like new. Perhaps Chevy really knows their stuff when it come to radiators. What say you?