On the way home from a car show last week the low coolant light came on. I kept an eye on the temp and topped it up with dexcool. Next day on the way to work same thing happened. No leaks, no steam? Checked the dipstick, and I got a milkshake. Onstar sent me a tow truck and got it to the dealership, where they told me that it came in on the last day of the 5 year power train warranty. They replaced the head although it passed a pressure test and gasket. Picked it up last night, and got halfway home when the low coolant light came on again. Checked the dipstick, and I got another milkshake. Now the warranty is replacing the whole motor. I am very interested in the cracked block I have. The motor only has 34k. I will post any findings they will share with me.