11 and 12 was a bad year for the 3.6L, between head problems and sludging concerns... Chrysler had their hands full! I've seen no cylinder head issues on the 2013 3.6L's. Although early 2013's did still have the 2012 cylinder heads. I have seen 2013 vehicles with the 3.6 still with concerns of sludging. There are TSB's and STAR cases open for those vehicles. 2014 3.6's are having a new issue with the oil cooler/ oil filter housing which for some ungodly reason has started to leak and creates a puddle in the valley between the two head's. I would recommend to anyone who has purchased a new model 3.6L engine to get a flashlight and inspect the oil cooler for leaks!