How do you know that? I am not saying they are or not dirty but some engines with low tension rings seem to be prone to higher oil consumption regardless of oil used or OCI.Here’s my experience. I’ve run 5k mile intervals from day one with mostly Mobil 1 and Valvoline bought at Walmart. My engine internals are spotless. My pistons are not. Oil consumption started at 60k and has steadily gotten worse. I’m now at 120k and testing Valvoline R&P for the four intervals. It’s hard to blame the oil because of the low tension oil rings but I have to wonder if a boutique would have prevented this problem.
I am sure most of the boutique oils are high quality lubes but IMO it has been a long time since they offered any significant advantage over the major players when regular OCI are observed. I never did extended OCI and never will and never had any issues on engines I have owned since day 1 that required or would even benefit from "cleaning" unless there was a design flaw of some sort like the early Honda VCM engines. JMHO