Contamination of extended life coolant on GMC Yukon XL Denali

Problem Description and Possible Solution
Extended life coolant may become contaminated and require cooling system service before the recommended 100,000 miles.
Problem Data
RepairPal Verified
Average mileage: (–)
10 model years affected: 2001, 2002, 2003, 2004, more2005, 2006, 2007, 2008, 2009, 2010
10 people reported this problem