flight deck fumes...phooey
Well, not entirely phooey, but lets get real here.
Oil odors/fumes have been prevalent in jet transport aircraft since the very early days in Boeing 707's, especially the early design turbocompressors used on the straight pipe engines.
I can recall several times when oil in the t/c duct resulted in smoke/fumes so thick (briefly) that I lost sight of the First Officer in a blue haze.
It was 'supposed' to be a better idea to use engine bleed air directly for cabin pressurization with improved engine oil seal design, but clearly as seals wear/engines develop higher time, leads to a few unsavory odors for both crew and passengers.
Look on the bright side with the 146.
At least when you smell the oil fumes, the engines are actually running, instead of winding down...as has happened with several in the past.