With absolutely no warning, the 6.2 liter V-8 engine with 28,500 miles on it seized up solid and would not run. I was stranded in heavy Christmas traffic and completely blocked one lane. It was an unsafe situation. I had to summon a wrecker to come and tow the vehicle, and I called 911 for police presence to alert and direct traffic. The vehicle was at the Chevy dealer for a month while they installed a new engine. The dealer never fully confirmed what the cause was — I don’t believe they really know — and I only have 10 months of warranty left. I am concerned about another failure and thought I should at least get the warranty on the new engine re-set to 60,00 or more miles.