While inspecting the front 3 spark plugs (bank 2) on a 2GR-FE (2009 Toyota Venza), I noticed the spark plugs have oil along the entirety of their threads.
There was no oil pooling the the spark plug tube or on the ignition coil packs (just a few drops/smears here or there).
There was wetness at the spark plug tube seals and when I blew it out with an air compressor, some oil droplets splattered everywhere.
There is no perceived drop in oil level between oil changes.
Seems not ideal, but does it look like it's ok to forgo opening up the valve cover(s) and replacing spark plug tube seals for now? Since there was no pooling I'm thinking it could be a slow leak due to age.
Some oil glistening on spark plug tube seal at valve cover, and a drop of oil at the spark plug, but no pooling:
Oil residue on seat and threads, with spark plug removed:
Just for fun, endoscope images from inside the cylinders:
EDIT: Pics of cylinder walls and cylinder head taken with a 45 degree mirror in front of the endoscope. Only the middle 1/3 crescent in the images is relevant.