The temp needle on my dash(98s70T) goes to the 3:00 position when the car has warmed up.......in warm or nice weather. if it gets cold, it will only go to the 3:30 position, and when its very cold(around 35-40F or less) it will only go to the 4:00 position-even though i'm driving down the highway and the car has been on for an hour. fuel mileageseems poor when this is going on.
ect and thermostat are new oem.

I believe this is affecting my fuel mileage. isn'tthe needlesupposed to go to 3:00 once warm no matter the outside temp?

 

Yes it is.
Are you sure they gave you the correct temp thermostat?

 

I agree with tech. My S40 did the same thing. When I went for a thermostat, they had one at 89 degrees and one at 92 degrees wherever I looked. I went with the higher and it went away.

 

My tem gauge on all three of mine stay right at 3:00 once it's warmed up. When I replace thermostats I go with the 92 or I might have even gotten a95 if Volvo makes one. I know I bought the OEM one called for in my car.

 

i've changed the thermostat twice now in trying to fix this problem, and the issue continues. the first was a oem(vernat) 87degree, the second one(in car now)a duralast 92degree. is there anything else that can be responsible? my coolant temp sensor is only about 5-6 mos old, (my mechanic said to change it when i got inspection) and the car was running fine till about 10 weeks ago. fuel mileage is not as good as usual. if the car is running and stopped, the needle will rise up. drive off, and it drops.

 

HMMM not sure sounds like a flow problem.
Any check engine light?