On 12/24/12, I called a mechanics in Bay area, he suggested me to have it fixed in local area, which is close to LA. So I drove the car to 'Big O tires'. They said that the thermostat was broken. It costed me about $540 to have it fixed. A little expensive but no choice. Big O tires was closed at 1PM on that day and they didn't have much customers, so they fixed my car quickly, in less than 90 minutes after I drove there. After that I drove about 1200 miles. So far so good. Today I got home.
Wish you all a happy holiday season!
BTW, turning on heat does help to cool down the engine, but the mechanics didn't want me to rely on that to drive home, because it is hard to know the damage to the engine.