I've had my car since April and have put 10000 miles on it. It now has 60000. They tell me the car has already been timeserted but it was'nt the heads that were done; it was the halves that were done. In June I took my car to the cadillac dealer and the said my car overheated because I have traces of exhaust in my fluid. I then took the car to my mechanic and he did'nt check that but did pressurize the system and supposedly found my lower rad hose leaking and fixed it. I never add any coolant. The car did warm up in the summer months while climbing hills at slow speed. When I climbed hills quickly though the car did not warm up. Now that winter is here the car cools down when I start traveling down the highway. It warms up while idling. I just think the stat is sticking. The dealer is telling me they need to replave the stat and the housing. I can not understand why they would replace the housing. They also said the housing was leaking. Like I said I never need to add any coolant and the engine was just presure checked in June. They also said they don't know if replacing the stat will fix my problem. Also since my car is running so cool it is wasting gas. I had too also put cardboard in front of the radiator just to get the stat to run between the first and second mark on the guage. Anyhow it seems to me that if I had a head gasket problem I would have no problem warming the engine in the winter. Hopefully someone has some ideas for me. I'm not ruling out a headgasket but it must be a very small leak if there is one and maybe it will not get any worse.