We are cross-communicating!

I disagrees as to what should come first, thats all. And I could have phrased it differently. Yup, checking the system for pressure holding capacity is part of determining why it boils over.

I was not suggesting that anyone should run only water and water wetter, only that the product is very effective and that was the example I chose. By the bye, it has nothing to do with political correctness, ever hit glycol in a corner at 150mph??? Not a pretty experience.

The water wetter does indeed increase the effectiveness of 50/50 glycol based coolant. It is indeed effective at lowering the incidence of "hot spots" in your block and shedding heat at the radiator.

I am sorry Baron but physics will prevail. A fluid held at a higher pressure will have a higher boiling point, period. The overheating problem you solved by going atmospheric, I submit, was "solved" by some other change that was made. Ditto for the PO who may have been masking another issue by using a higher pressure cap.

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Mike!