when it gets warmer outside(above 80) i notice my car lacking power and some detonation. after its been shut off for awhile the temp actually rises about 20 degrees. thinking i got a bad rust or calcium buildup. i contemplated draining the coolant completely and running upto walmart and getting about a gallon of CLR but dont know how good that is on seals, so i was just asking if there is any chemical additive safe for runnig in the coolant system to eat off corrosion and buildup.