I have purchased over 5-6 costco batteries for my cars and family, all of them lasted more than 3 years. Its possible that I might get one that will die sooner than 3 years, its OK, I will deal with it. Costco batteries are always fresh made and convenient to pickup when shopping at costcomy brother didn't anticipate any issues with the battery in 3 years yet 17 months later it was back to Costco for a replacement and $60 out of his pocket for the replacement because of pro-rating; Costco's current warranty...that and a previous poster reporting similar is the last of me buying any batteries at Costco...especially when the Walmart Everstart Maxx is the same manufactured battery here in ChicagoLand with a 3 year no pro-rated warranty...
Good luck with your choice
Bill