My Suburban was smoking heavily on startup !
Thought it was valve guide seals. However after replacing my knock sensors i noticed my intake manifold was full of oil. Saw that the passenger side valve cover hose going to the throttle body was sucking oil into the intake.
I blocked off the line and it hasnt smoked in 2 months,
I need to put a PVC valve in the line so i can remove moisture from that side !
Also i an Not loosing any more oil between oil changes.
Over. 230,000 miles on 2005 Z71 suburban.