Originally Posted by Mazmart

The claim made from PG is not that it lowers engine temps. What we've seen is an increase in temps (Without boiling). Some engines don't mind and may even like this, not rotaries. We attempt to do the opposite (To some degree) of what Evans does. We attempt to control our operating temps to what we consider optimum. Mazda Maniac pointed out some criteria in temps (Under load, high rpm etc). We don't like to see more than 195degF outlet temps on track or about 180 in. We even prefer 20deg cooler than that if possible. It's hard to do that with a factory Mazda thermostat.
Some would judge success on track as not puking their coolant all over the ground when racing, we like to see what a motor looks like over the course of time under arduous conditions.

Paul.