I've got a 06 2.8 CTS I've owned for a few years now. It use to over heat and I went through everything and fixed it all. New waterpump, thermostat and housing, radiator, all that and it worked out pretty good. Now years later it would drain all it's coolent out and I would need to refill it every week, week turned into every other day and now it drains it out the moment it gets warmed up, figured it was the thermostat housing since everything else isn't leaking, finally got around to pulling the intake off and everything pertaining to that process I.e., alot of fucking shit. Just to notice that is not where it's leaking from. I'm gonna Jack the car up here in a few minutes to see what I may see but I can see water on top of the bell housing, can't see a whole lot since gm decided that this model would be great if the only had a credit card width of space between the rear block and fire wall, then throw a shit ton of wiring harnesses on top of it, and then cover the smallest crack in the world with the intake manifold.