Do not have a dog in this hunt… but I will comment about this individual post. Also as an aside funny, , catch-can is a catch-all word for the MANY “catch can” designs on the market… with some highly touted vendors bad mouthing their own expensive offerings, and then offering a new and improved one. L. O. L.Curious, have you ever had a chance to look at the backside of your valves after some miles and when you have done the ritual 7/8K CRC cleanings? I'm just wondering what they looked like and if the walnut blasting would even be necessary? Also, today's oils seem to be getting better and better at limiting carbon deposits. I'm hopeful with 3K mile OCI's with a good oil (keeping current with the API certifications as time passes) and with yearly CRC-type cleanings I won't have to worry about carbon deposits down the road. Don't know if that's a pipe dream or not though.
Referring to seeing valve deposits:
Back in the day, I built and rebuilt several engines and every one had valve deposits. Some grossly so. Only powered wire brushes would remove the deposits. Even the piston heads had deposits. And those cars had no PCV system. Their blowby went straight down onto the road.
Get my drift?