180-degree Drilled TStat
On 9/1/2003, I installed a 180-degree drilled Thermostat. Now the car will runs a little cooler which should help with the longevity and reliability of the vehicle. It was a $10 mod and it is worth every penny. Only problem is that I was developing leaks in my thermostat housing, but it was easily fixed by installing the Tstat O-ring the correct way. The instructions I used made it look like the O-ring was installed by laying it on top of the Tstat. But there is a groove in the O-ring for the edge of the Tstat to go in. Once I figured that out with the help of a fellow Grand Prix owner, everything was fine.
However, now that it is colder, the drilled part of the thermostat is making the car take a long time to warm up. I may switch to a non-drilled thermostat some time.