by what iyou guys are saying it sounds like valve guides/seals , sounds like its givin u a hed ache. Its not your turbo , as for pcv they can get gummed up take it out clean it wth solvent . oil grade is ok if its winter ,10 w 40 for summer ,i know how cold it gets used to work in fort mac oil grade was a difficulty in our large cat 3500 series engines [78 liter 2300 hp] in cold weather. but your symtoms sound like guides seals
hope this helps