As a reminder for preventive maintenance, anyone with a 6 cylinder E39 might want to replace their cooling system if they are over about 120,000 miles. My Radiator neck cracked at 150,000 miles and left me without wheels for a couple weeks while I ordered parts and did the repair.

Shopping list includes radiator, thermostat, fan blade if chipped, shroud if chipped, major hoses, water pump, bleed screws, small bleed hose across the top of rad, fasteners, fan clutch if you suspect any problems and new coolant.

My 535i radiator neck cracked the same at 150,000 miles, so I think that 150,000 is the end of the radiator life cycle.

Best,
RonH