adding the coolant also raises the boiling point of the water. so you arent boiling at 212, also the pressure of of the system also raises the boiling point. An LT1 F-body runs at well above 210 for some stupid reason GM thought that was fine, the high fans come on at 230 LOL but as long as you arent boiling and not too hot to hurt the motor, id say around 215-220 is borderline, too hot. 230 only for a VERY short time.