convert farenheit to celcisus, I think the celcius number for your car should be about 85 to 90 degrees on average, moving from there to 100 ocassionally on hot days then back down. If you stare at it too much you'll go nuts and hit another car ;-) Think about 90 degrees celcius on average. That is the case for my 1984 380SL which is similar.

Relative to the other observation about the oil gauge being pegged and temperature off, it is likely that there is a bad ground behind the instrument cluster or a problem with that portion of the instrument cluster, or connections that need cleaning.