Driving home the other day; the temp gauge just pinned past hot. Drove the 2 minutes home and shut it down. Next day check the rad fluid and its empty. I refilled it and ran the car about 30minutes and couldnt find one drip. Drove the car for another 30 minutes and the needle stays just before the center of the gauge(norm). Wake up this morning check the level in the rad. And its halfway empty, refilled; drove to work w/ no overheating problems. WTF?