I never owed a car that would overheat just because you drive fast and I've probably owned 20 or 30 different cars. Some new, some old and high mileage, economy cars, sports cars, etc. None of gthem would overheat just because you drive on the highway at, let's say 80% of the red line. I also never owned a french car or a turbo diesel so I just wanted ot know if it's "nomral" or if anybody knows what can be the cause. I am curious though why if it's crap in the cooling system does it not cause trouble at slow speeds?