What type of plastics are used in automobile radiators, their max temperature and shear points connected to aluminum edge. We have a earlier 06 Cobalt, the plastic sets on two rubber boots and the plastic actual is inside the radiator. The plastic sheared off on one side and the radiator drained all coolant. This seems like an unstable engineering design. The Service department said it is road hazzard and not warranted. Also was the plastic bumper longer under the car than those produced after January 06, a design change?

Optional Information:
2006 Chevrolet Cobalt 2.2

Already Tried:
Getting it fixed and having engine sent back to factory, did thermal damage to pistons and head. Temperature reached 380 degrees F. At first the just fixed what they could see, when my son drove it home he made about 5 miles and it died. Now the Service department found coolant in the engine oil (Duh). I asked them too check that out before we picked it up and they said that engine can handle those temperatures without deformation. Guess not!