Tried to search for this exact problem before posting but didn't find it in the forum.
Anyway, my car is a 2006 WRX with manual transmission (doubt that makes a difference). Just bought it. It's nice and cool while running down the highway, but when it idles, especially in hot weather, it starts overheating. Normally the temp gauge sits at the first hash mark 1/3 up the dial... but when sitting in traffic or idling, it can easily climb past the next mark, 2/3 the way to the top. I haven't let it approach the red yet but I'm sure it would if I let it sit.
It doesn't take long for it to overheat either... a couple minutes and I'm up there. If I start moving again at a good pace, the temperature backs down into the normal range. Anyone know what's up?