On my 2007 GP in the past I've done the following:
- New T-Stat. 195*F which is stock.
- Bled cooling system with one of these: https://www.amazon.c...or funnel bleed
- Checked/re-checked coolant levels.
My issue is this: the car gets up to temperature just fine. Once the T-Stat opens and I'm traveling at highway speeds (55mph or so) the temp on the gauge and inside the vehicle drops. It isn't cold per say but it's chilly enough that my windshield won't get fully cleaned off. My past W's were always HOT in the winter and this is lukewarm at best. During the summer the temps get to the middle mark and stay there even in extreme heat it rarely moves above the middle. Now I'm lucky to be on the first hash. (there are 4 bigs lines on the 04+ so I use the middle one as 'where it should be')
This car doesn't have the metal cap so I'm thinking maybe replace that next.
The only things done to the car are intake and I've removed the engine cover.