I have a 2004 Pontiac Aztek 2WD with 215,000 miles. For about 4 monthe the temperature would run a lttle hot especially at stop signs or traffic. Yesterday the "Service Engine Soon" light came on. I stopped at Auto-Zone and they said it was a thermostat problem, low coolant problem or ETC sensor bad. I took it to Pontiac dealer and they dismissed the Auto Zone codes and said it was an intake manifold problem that could cause oil and anti-freeze to eventually mix and ruin engine. The Service Manager said it was a common problem with this vehicle. I ahve talked to one other person with the same problem. Is the dealer being truthful or just trying to get extra repairs from me. If it is the themostat I would think that the manifold would be OK. The stimate was for $600/700.not including a flush if necessary. Any thoughts would be appreciated.