Congrats on the new car, Patman!
My best friend last summer traded his 2010 Cobalt SS turbo for a 2007 Corvette. His is silver with a black leather interior, 6-speed manual, and the see-through roof.
His has about the same mileage as yours, and he paid a bit under $27k I think. He runs M1 5W-30 in it as well.
He's been nice enough to let me drive it a couple of times, and man those cars are a blast - very fast, but easy to drive! A week ago we also did a day trip to the US with it, and they are very good highway cars as well - I'm impresed with its overall abilities.