Looking around the GM boards, it seems the L86 in my Yukon has some coking problems. I've seen some photos after under 10k miles that are concerning. Looking into installing a catch can. The GM forums are all over the place on the opinions of them.... "Trust the engineers," "Have to have one," "GM will void your warranty," all sorts of stuff. I'm curious what the thoughts are here on them? $200 piece of mind, snake oil, or truly an intake valve saver?