I'd make a service call to your dealer. This isn't normal. I have a 2011 6.2 as well. I live in Texas and it never gets below 30 lol here in Htown, but I ran synthetic after 1000 miles just to be safe.
I bet once you put on some 18's or 17's it will really haul ass^ my 22's are like boat anchors but they look good. I have a set of Z71 18" oem wheels and tires I put on, it feel like I gained 20-30 hp over the 22's lol.