I had a friend tell me that the most important thing to do every 30k miles or so is flush all the fluid. he said that if the pH is off, it will ruin the head gasket, which is a much higher cost to repair. I'm assuming since he is talking about head gasket he means coolant.

Anyone ever heard of this before?

 

Sure have. but let me tell you this you can buy test strips to test the ph. If the level is ok you can continue to run it. When you have a hundred or more units in your care you look to save maintenance dollars and that is one of the ways. If the ph becomes either to acid or alkaline you want it out of the system because things suffer, usually radiators. Diesel trucks have coolant filters as well as anodes to help extend the life. My 2 cents. Kotzy