Valve Stem seals replacement

[Igottaroll]

So I am going to be doing my Valve lash adjustment this week, need to replace valve cover gasket anyways. I (2013 6.7, with 167K on the clock. I tow somewhat heavy) I do get a little blue/black smoke on start up here & there. (No blow-by seen with a teapot test)
How often does this come up on 4th gen's?, I keep seeing articles & concerns on 2nd/3rd gen, but very little on the 4th gen.
Thank you for any input.

 

[sag2]

Does it use any oil between oil changes? If not, leave it alone.