I am new to Mercedes Diesel Engines, and have gotten a lot of helpful information of the individuals on this site. So, rather than give myself a heart attack with my quasi hypochondria in regards to my car, I figured I would ask someone who knows. As such, I have a 1987 Mercedes 190d 2.5 Liter Turbo, and I was wondering is it normal for the engine to operate at normal temperature while driving (IE 65 Degrees Celsius), and when I come to a stop and idle for approx 3-5 minutes, for the engine to raise temperatures 15 degrees Celsius and idle at around 80 degrees Celsius. Both temperatures are well within the cooler operating ranges, I was just wondering if the fluctuation was normal, or what I should be looking at fixing.

Thank You,
Phil