I have had original formula Evans NPG in my 1995 Magnum 5.9V8 since 1998.
It does work as far as cooling. It does not transfer as much heat as water.
It did not reduce pinging via what Evans “nucleate boiling”.
An engine idling at a coolant temperature of 260 degrees is quite smooth compared to either 195 or 205.
You can take the fan blades off and run for months during seasons where AC is not needed.

Around year 2003 my drivers side plastic radiator side tank began leaking and I replaced the original radiator. I am not sure whether the Evans NPG caused this.

The Evans NPG changes color over time. Evans says not to worry.