Wanna know why I am emphatic about the viscous fan?? Two years ago I went to Indiana to see my sister and every time I let the car idle for a while it started to overheat - started driving and the temp went down. The viscous fan was still turning pretty fast but I called my mechanic friend long distance and he said to change it and sent one overnight to me at my sister's. Changed it in about an hour the next morning. The new one locked up real nice when the engine was hot - you could hear the air rushing when you revved the motor. Solved the problem. It's hard to tell if the fan is actually at engine RPM when it is supposed to be locked from heat - His symptoms are so much like mine (but a lot worse) - that's why I think the fan is slipping when it should not.Time will tell if I have egg on my face!