I just recently bought my 03 cts. It is very clean and has barely signs of wear and tear. No rust on body but the other day I was doing an oil change and saw that where the unibody is welded to the subframe is almost completely rusted out. It is exactly in the same place on both sides, right behind the front wheels when it starts to curve up. The rest of the underbody has no rust issues at all! It is past the mileage for the rust warranty. Anyone come across this or have any suggestions?? Please help!