My 2007 ML63 has suddenly seen the engine oil temp rise. The car is in Spain, where the current summer temperature is 37 degrees c. On a journey last week, the engine oil temp rose to 137 degrees. Even at 100km/hr, the temp did not drop. Normally, when the temperature is around 18 to 23 in winter, the temp is around 100, and normal spring/ summer temp of 30, rises to around 113. Is this purely down to this abnormal hot spell, or something wrong with the cooler etc. No warning lights appear on the dashboard. Any other experience such as this?