Quote Originally Posted by JohnM View Post
They don't want to add another maintenance item that may need attention earlier than the valves themselves. An issue with the catch can will raise a check engine light because it is related to the emissions control system.
There are OCC design that drains the oil back to the system.. diesel engines also suffer from carbon build up but can withstand..

For my mazda skyactiv, i use petron blaze fuel... i noticed that almost zero soot formation at the tail pipe.. not like before when i was using xtra or xcs unleaded.. less soot means lesa carbon build up at the intake valves