the gm fix was to remove the oil pan and cover the afm oil pressure valve located in the oil pan. the valve sprayed to much oil onto the oil control rings. along with this gm replace the valve cover to change pcv flow. to clean the clogged rings the spark plugs removed and a combustion chamber cleaner put into the cylinders. if you could do the work yourself its worth a shot. a shop would charge 9 hrs labour to do this. at this point the repair is not a guaranty to solve the problems.