I've run K&N filters, as well some oiled foam filters off and on over the years in various applications. I've never found the intake or the piston on the CV carburetors to be oily or oily/dirty as a result. I find it highly suspect to think that K&N oil only travels onto the wire of the air mass meter. Not that I do not think oil comes off, especially when initially installed with excess oil. But I don't find oil soaked intakes and such.

'97 T-100 SR5
'86 Toyota's, the variety pack (all gone)