Hi guys,

I went ahead and bought a new 87c Behr thermostat on Friday and installed it this afternoon because my mechanic refused to swap it out under warranty. To my surprise, the thermostat that my he put in was rated for 75c! I don't know what brand it is, but stamped on one side was "G7 2.08675 BTT Made in Germany." It was immediately apparent that the check valve was broken off by force, as the four strong metal tabs that hold it in place were badly mangled. What was left was a small hole that would seep coolant when the thermostat was supposed to be closed.

I called up my mechanic to find out what the deal was and he blamed me for breaking the thermostat which was the wrong one to begin with! So now, in addition to using the wrong coolant and spark plugs, he used the wrong and very broken thermostat!

Anyhow, I took the car for a spin and found that there was no soot at the tailpipe to report, and the area under the air flap was clear after two days of sitting. The car felt more responsive with the new thermostat, but it might be some kind of placebo effect. In regular driving conditions, the engine temperature is now where it was before this whole ordeal started (~87c) and slowly creeps up to about 100c when idle for a while, at which time the aux fans turn on.

Lambda will be checked and adjusted as needed tomorrow, followed by a fresh oil change and test drive to see if my fuel economy has been restored to acceptable levels. After that, I will try to find a place to tackle the odometer gears and will also be on the quest to find a reputable and knowledgeable mechanic!