You did not mention the age / mileage of your car, so I'm not sure if my own experience is any relevant. Around March 2001, my 156 (2.5 V6) started running at a higher temperature than had been normal throughout my 2+ years of ownership. At the time, my car had clocked approximately 65,000 km.
I had never seen the temperature rise above 90, and now the car seldom ran below that temperature!!
You could say that I am absolutely a**l about checking, and topping up, the engine oil (I check it every weekend!!), so the issue of low oil level never arose. My concern was the head gasket, but I never saw any tell-tale signs of oil-in-coolant or coolant-in-oil.
The dealer insisted that since the car was not actually "overheating", there was absolutely nothing wrong with the engine. However, I was privately informed by one of the mechanics at my dealership that, in all probability, the radiator core had deposits on it leading to a reduction in the flow rate of the coolant.
I had the old radiator reverse-flushed a couple of times and noticed some improvement, but the temperature still stayed above 90!! I decided to cough up the cost of a new radiator in June 2001 and, since that day, the operating temperature on my car has never risen above 90!!
While not identical, I hope this account of my experience helps in your case.