I have an 07 new body Chevy Duramax 6.6 LMM with 204k miles. I just changed my oil, staying with rotella 15-40 but used a K&N oil filter Instead of the AC Delco because it wasn't in stock. Proper oil capacity, no leaks but noticed the truck making a ticking noise when in drive. Got significantly louder and truck became sluggish with oil pressure dropping just below 30 at a red light or letting off the gas and cruising. Nephews a diesel tech and he said possibly the filters micron count. Haven't changed it yet because it's cold as hell out and seriously doubt the filters the culprit. Sorry for the long post but figured I'd get some more information before I start throwing money at it. Thanks Chevy bros!!!!!! #roalcoal
FYI it doesn't matter the temp, the knocks there to the point that I won't drive it unless it's to the shop.

 

K & N oil filers are fine as are most, with the exemption of Frams. The high-end Frams MIGHT be okay, but I stick with WIX XP's., Purolator One's or AC Delco's myself.