Here is the latest report on my JK. I bought my Jeep new in 08 and have had UOAs done since new. Initially I used 5w-20 as recommended. I noticed the engine made a lot of noise on hot desert days so I started using Penzoil Platinum 5w-30. It quieted the engine down and seemed to protect the engine well. I tried Rotella T5 10w-30 in 2010 for one change then went back to PP. The copper levels were always high but were slowly declining. I've noticed on other UOAs posted that copper seems to run high in the 3.8L in the Wrangler. This last oil change I could not find PP so I tried M1 5w-30 High Mileage. My engine seems to like it. Copper dropped to normal levels and all other wear metals look good. I change oil roughly every 5,000 miles and use MC FL-400s oil filters. My Jeep spends a lot of time in the desert and hauls my pop-up camp trailer at least a couple of times a month.