I've pretty much done everything to try and discover why my Jeep is overheating after an accident and new radiator was installed. New fan clutch, checked the lower radiator hose spring, thermostat, air pocket, etc,..... Everything points to the radiator. As a last ditch effort prior to replacing the radiator, I tested the coolant with a Prestone knock-off tester sold by NAPA. The guage says I am protected down to -40 degrees F and up to 270 degrees F which sounds great but I also understand that too high a concentration of coolant can reduce cooling efficiency. The concentration should be 50/50 coolant to water but 70/30 is too much. While my readings seem somewhat high, I don't know how to interpolate how high is too high. Can anyone help?