My report:

I could feel some rocker play, so removed some of them... conclusion: rocker bushings are begining to fail BUT, not everyone, just front ones ( pistons 1 and 2 ). I can notice burnt oil layer around, everything dark there. Including on bushing top area and rocker

Some oiling failure ?

dunno, but I have allways got oil gauge between half and top reading, never less than that, which is better than any average reading. I got half gauge reading just when got lifters failure, but the rest of the new engine life gauge has got 2/3 and top readings.