The last pontiac I had went over 300,000 miles with the original radiator and I didn't have to baby it either they have metal radiators, I sold that car last year. I think the BEHR radiators that they put in BMW's and many japanese cars are defective from the start. Here's a thread showing how many people had the same problem I had.
http://bimmer.roadfly.com/bmw/forums...4216982&page=1
Also
http://home.earthlink.net/~hainesinutah/radiator/