Running too cool?
 

Is it possible for the car to run too cool? It is getting into fall here, so the daytime temps are much lower. I have a relatively short drive to work, so the car is not reaching the normal operating range as often as it was before. My fuel mileage has also gone down.. so I am wondering if my oil thermostat is opening either too soon, or is stuck open...

The oil also smells a little fuelish.. as if the engine is running too rich right now...

Short of checking temps at the oil cooler thermostat housing.. is there a test? Has anyone run into a thermostat that sticks open? Would that create worse gas mileage (like in a water cooled car)?

What is your winter/fall driving experience with the temp gauge? Mine often only reaches halfway past the first two marks... (7:30 or so on the gauge, or a little past 122F (per the P-car.com DIY page on the oil gauge)...

TIA!

How long is your journey?

Mine tends to run just under the second mark, winter or summer. The difference is that in summer, it doesn't take much traffic - or much spirited driving - to get it at 9 o'clock.

If your thermostat is open at all , warm oil will go up to the cooler .
When you get to work , feel up your cars right front for warmth .
If the right fronts no warmer that the left front , I guess that its not the thermostat .

The oil will smell of gas if the motor never gets hot hot .

I've had my C4 for two winters, going on my third. I find that often the temp just doesn't get hot enough to open the thermostat. Even with some spirited driving. It generally requires sitting and idling for a while to get the temp up enough to check the oil level during the colder months here in New York state.