Drain some oil out and run a bunch of motor flush in it. Idle it for 10 minutes, and change the oil. Then get a can of B12 chem tool, pour it in a dog bowl, & pull out your pcv valve leaving it attached to the hose. Have a buddy keep the rpms up on the motor while you let the pcv suck up the chemtool out of the dog bowl. That should yield a good amount of smoke, but your motor will be nice and clean if you have to rebuild.
One time My kid brother topped off to the filler cap, SAE 30 in the lawnmower and it was smoking blue like CRAZY. It was ruined after that. It would only run with the oil fill cap off for some reason, and it's no good mowing the lawn with oil and grass/dirt spattering everywhere.