Think about depth filtration of the K&N or paper (as opposed to micron
filtration with a thin membrane of some sort)  from the viewpoint of a
small particle.  Imagine that the scale of a micron size particle
traveling  through 1/8 inch of oil soaked fibers as a hurricane trying
to blow a tennis ball through a 1/10 mile of a forest of stickum coated
Aspens.  If the first tree hit doesn't get the ball, one down the line
will as the speed of the ball drops. Oil wetted depth filters combine
capacity, efficiency, and high air flow unlike any other.

If it weren't for the oil, lots of particles would get through by
bouncing off the fibers or clog the entire depth of the medium if it is
too dense (i.e., dry paper), but with oil wetting they are grabbed and
held so you can have a looser mesh that allows for better air flow AND
excellent filtration.

--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT