This drain plug has been leaking forever, the drain part is reverse thread and normal thread into the radiator. The thread into the radiator needed more PTFE.
Due to topping up with water over the last couple years the coolant was starting to get hotter than normal when the engine was pushed. With the new coolant G48 with suitable BMW specification the needle stays steady on 80ºC when pushed hard. When testing on idle at a standstill the fan kits in at 88ºC and comes down again nicely to the low 80’s.