My 560 typically runs at 85-90 however on a recent hot day while heading up a long steep hill at 60mph the gauge went to 100 and sat there until I had finished climbing when it went down to 90. I always drive with the aircon on as well. Just today I have had a new radiator fitted, with the reinforced necks so it will be interesting to see if this alters my temps at all. If you are really worried about your temps you should get a proper gauge to test with.

Matt.