Hmm, that's weird, mine doesn't fluctuate like that once it reaches temp, it sits just under 90 (82 on diags) regardless of driving. But does start dropping off as soon as I stop, but I don't tend to leave the engine running if I'll be stopped for more than about a minute. However it wont reach temp until I give it a boot, can do 30+ mins of slow town driving without it hitting 90, but once it reaches that seems to regulate well. I don't like giving a cold engine a boot but it seems the only way to warm it up. Of course neither of us have the EGR cooler adding heat to the coolant either which won't help warm up.

I've never seen mine hit 110 even in the height of summer...but did hear the fans quite often, don't think they were always for failing regens.

Would be interested to know if a new stat helps yours to regulate better, but I wouldn't say that's definitely the problem.

My 08 focus does this, it is exaggerated by the cold weather as the heater matrix is a radiator dissipating heat, completely normal 😊