Originally Posted by crystalworks

I preemptively replaced the one on our N52 (5 series) at 185,000 miles. I doubt the one I removed was original but not knowing when it was done... I did it. Got a Pierburg from FCP euro. When I buy any used BMW one of the first things replaced is the water pump, thermostat, reservoir, and majority of the cooling hoses. Just had to replace the radiator last weekend at 195,000 miles. So I did the trans thermostat and mount as well. All about pre-emptive replacement. Though definitely not the most cost effective method of ownership, it keeps me from getting stranded out of town in my 15 year old vehicles.

Fortunately it was not the crazy expensive version being discussed here. *phew*