My buddies 2011 Chevy 1500, which was bought brand new and has never towed a day in its life, all easy highway miles. 120, 219 miles total and 5,750 miles on the Castrol Edge HM 10W30 and Fram XG filter which was drained today and replaced with Supertech Dexos 5W30 and a Baldwin filter. I always noticed the tailpipe was sooty, but never really gave it a close look until today. The inside of the tailpipe has a good buildup of soot, and the underside also. I cut open the Fram XG filter, no gunk or sludge at all inside but the filter element was extremely black for 5,750 miles. Should the tailpipe or filter element be any cause for concern? Any of you with vortecs notice this also? What mileage should the spark plugs be changed in these engines? Besides the sooty exhaust, the truck still runs great and gets great mileage, has never had any problems or any CELs come on in 120k miles.