that was happening to me until I put in the new PCV.
Give the additives a try? No harm I'd say.
I'd recommend a half bottle of Seafoam in the crankcase and change the oil after about 300-500 miles. Did wonders for mine. I've used MMO and it worked well too but wouldn't recommend leaving it in too long. I've heard people will sub a quart of MMO for a quart of oil but that seems a bit drastic to me.