01 yukon 5.3. Only smokes after long idle and quits after i take off maybe 3 seconds of smoke. Changed to the new style valve cover and O2 sensors

[Grant17]

Smoking after long idle. Updated valve cover and o2 sensor

 

[Blackcar]

Does vehicle smoke after setting all night. At start up.

 

[Mudsport96]

The inside of the manifold lools like this, so there may be oil sitting in the low spots. And it could take some time for it to all be pulled out by the air moving through the engine. You could try removing the manifold and aee if you can dump it out, or just wait to see if it slows.
I reverted both of my 5.3s to the 99-02 covers with the actual pcv and have little to no issues. The Tahoe has almost nothing in the catch can i installed when checked biweekly. The Silverado will have one to three ounces biweekly, but it also has over 400k miles on the clock.