60 to 70c is low, not good at all. This will lead to carbon deposit due to incomplete combustion. MBs usually run well between 80c-95 when the thermostat and cooling system is working properly.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT