It was determined that the radiator had not 1 but 2 small cracks in it that could not be properly repaired. I am not certain about this but it seems that these were stress cracks near the petcock on the lower passenger side of the radiator bottom.

I have owned many vehicles over time and have never had an issue with a radiator on any one of them. The dealer strongly suggested that I replace the radiator to prevent possible issues later. The last truck I owned had 225,500 miles on it since 2001. My current Silverado 1500 has a 100,000 mile 5 year Power Train warranty of which there is approximately 11,000 mile remaining. The cooling system is not a part of this warranty and thus I paid for the repair. The dealer did check for warranty but determined it was not included.

The truck had been driven by my son for the first 84,747 miles at which time I purchased it from his leasing company. It was not leaking at that time.

Issue resolved at considerable expense. No more leaks. I did get to keep the original radiator.