I dont let the temps go above 220, I have 7 aftermarket gauges so its easy to tell when something is wrong. After 2 faulty pressure testers I got one that finally worked and found a new leak on the lower rad hose and can still here hissing near the back of the motor. When I tug on the hoses back there the hissing gets louder or stops so I guess its a hose I cant see. The pressure tester made things a lot easier tho and gave me more time to feel/look around before things would normally get too hot.