From June 1978 the OM616 only had an oil cooler if it had airco. Before June 1978 it was standard. Euro 240Ds rarely had airco, hence no oil cooler.

The oil cooler only works if the oil temperature rises above 95ºC. It only works in extreme conditions (when the coolant doesn't keep the temperature down). At 95ºC the normal thermostat is fully open.

The smaller oil cooler was standard from February 1979 on the OM616 (with airco).