We are getting a little side tracked here considering the OP has an oil control issue not a carbon issue, but I'm enjoying the discussion.
I've heard good things about GM top engine cleaner, but have no personal experience. I remember back in the 90's having a 1980's something Ford in the shop. Had a pretty bad carbon issue, one of the guys had run a couple of bottles of whatever cleaner we were using at the time, through what we called an IV drip system into the PCV line. Still had issues. So I sat out in the parking lot and SLOWLY ran a gallon of water through the intake right down the carb. That did the trick. Like in
@Matt69olds story there was a big grayish black streak of crap on the ground that came out of the tail pipe.
@AuroraGirl I understand your way of thinking there and to some degree I agree, but keep in mind in a shop environment there isn't always the luxury of pulling all the spark plugs out and squirting in your decarb chemical of choice and leaving overnight. Of even fogging the engine and leaving overnight. I've fogged engines with AC delco X-66A (which by the way is bad ass stuff) and left them sit for an hour or so. Water works because it thermal shocks the carbon, basically making some of it brittle and then it comes off, or at least that's the theory. But again got to be careful with water!