One good way to check is to find the Last 7 digits of the VIN of the car your thinking of getting and going to realoem.com or pelica parts.com and putting that in to see what the factory parts were. If its a 525 or 528 made before 1999 then it's most likely an M52 engine which came with plastic rad and expansion tank. An aluminum rad is around $300. Definitely worth it for prolonged life