I didn't run a catch can for the first 70k miles. Routine checking of charge pipes, found more oil in them than I'd like so I got a catch can. 3k miles later, about 1 tbsp of oil. I'm not terribly worried about it caking on the valves or causing knock, I just don't want that nasty shit in my charge pipes because it's annoying to pull off a hose and find oil. That said I'm installing aux fuel this weekend and removing my occ in the process.