As an aside, because the wife and I both have engineering degrees we are technically inclined and therefore want to know the details as to why things go wrong. This is what my wife told me after talking to the head mechanic (since I obviously wanted the reasoning behind the sudden 180):

What Brooks figured out based upon the other dealerships work, which also included pressure testing the head, was that the block is the most likely problem. The 2.4 L engine (this is the same engine in the base solstice/sky and I also believe the new Malibu) has steel sleeves in an aluminum block, and apparently the steel sleeves can crack, causing a mysterious coolant leak into the oil. The head mechanic down there is very familiar with this problem since Cadillacs with a similar set up(I don't know what years or models) also have exhibited this problem. So there, I learned something.

In any case, nothing is appoved yet, but we should know in a couple days whether or not GM gives the green light.

In response to onehundred80 - ouch, and I don't blame you.