Oil fill cap with air/oil separator

An oil fill cap for an internal combustion engine, said cap comprising a cap body for mounting to said engine for receiving an air and oil mixture therefrom, said cap body defining a plurality of passages therethrough, including an upstream passage and first and second downstream passages meeting at a separation junction, said cap body defining a separation zone at said separation junction and receiving said air and oil mixture from said engine through said upstream passage and sending separated air to said first downstream passage and sending separated oil to said second downstream passage, said first downstream passage directing said separated air to a first exit port from said cap body, said second downstream passage directing said separated oil to a second exit port from said cap body, wherein said separation zone comprises an impaction and separation zone comprising one or more nozzles accelerating said air and oil mixture axially therethrough and axially rectilinearly against impaction media to separate said air from said oil by inertial impaction, wherein said separated oil and separated air diverge from each other at said impaction and separation zone;

• the upstream passage is parallel with a second sub-portion of a second segment of the first downstream passage;
• the second sub-portion of the second segment of the first downstream passage is the last passage portion in the cap body that the separated air flows through;
• and the entirety of the first exit port's elevation is lower than the impaction media, when the entirety of the media is oriented above the one or more nozzles.