It sounds like you have thermostat that is stuck open...The car should get to midway point on the gauge and then just stay there...JasonI totally forgot I dumped a can of seafoam into the fuel tank last week.That's why the spark plugs look black.
Oh I didn't bring the post up to speed on why I tore into it.
My 10 hour old engine oil with Marvel Mystery oil now has a hit of Gas in it.
I was reading that cars run rich in cold weather and some gas will get pass the rings and into the crankcase.
This car just does not like the cold weather. It's not getting up to full temperature to burn off those gas vapors in the engine oil.
When I'm at a stop, the temperature will go to the half mark where it supposed to be,but when in motion it drops 2 notches.
I'm just going to change the engine oil and put her to rest for the winter.