Originally Posted by Efthreeoh
Coolant changes have nothing to do with pump failure. Heat loading causes the pump to fail.
The only way to be assured when to preemptively change the pump out is to have the car scanned regularly with a BMW-reading scan tool (i.e. on an OBD2 reader) and look for pump low-speed fault codes. Once the codes start to appear, change the pump because it will fail eventually.
Seems like wise words....