I have a 2006 Kia Rio 1.6L. Yesterday I put in chemical flush in the coolant reservoir since I’m flushing the system out on the weekend. I drove it once yesterday and the temperature increased as normal. Today when I drove it, the temperature was still at C after about 5 minutes, after about 20 minutes of driving, the engine finally got up to near normal operation temperature. What could the cause of this be?