Anyone noticed that you can actually run the engine with a more advanced ignition timing when the coolant temp is lower, especially below 100C. With a more advanced ignition timing, I'm getting better performance in terms of power and fuel economy. I'm don't know about MBs designing their engines to run up to 105C/110C but I'm certainly getting better performance when the temp is around 85C-90C in a tropical climate. If MBs were designed to run in such high temps, why the need to have different parts (temp sensors, fan clutch, switches, etc.) for cars in tropical climates? I was also experiencing wildly fluctuating temps (85C right up to 120C) before using the appropriate parts for the tropical climate. After the upgrade, temp remains around 85C to 90C in ANY conditions. IMHO, with a proper cooling system, temp fluctuations should be kept to a minimum.