I have come to automatically replace it every 100,000 miles. I think the more heat/cool cycles on the system, the quicker they stress crack.


2002 X5 3.0 382,600 miles
2014 428i 70,700 miles


2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles


1970 Firebird Under restoration