I have a 2008 grand prix with the 3.8 v6 base model with 70k miles. i noticed that the car is running a bit hot in traffic but highway driving its on the half mark. i have changed the coolent temp sensor and the thermostat with ac delco oem parts. did not fix the problem. also did a full coolant change before past winter. i have no idea where to look for from here. it goes beyond the half mark and the fans kick in dropping the needle back to the half mark then climbs up again. my next thinking was that could it be due to a little bit sticking radiator cap causing the pressure inside to be more than the oem pressure so it tends to heat up a bit? does our cars have two stage fans ? kicks in at a low rpm at a lower temp and higher rpm at a higher temp? i have no idea what to look for from here. i also have pluggs wires throttle clean and air filter replaced. and car is running smooth just needle shows hot.
here is a picture of the needle when the fans start to kick in. any help would be highly appreciated.