Nissan Motorsport International "Oil Separator" Oil Catch Can for Nissan Skyline GTR (BCNR33 & BNR34) The Oil separator was developed for circuit-driven users, separating oil from blow-by gas which is sucked into the intake from the head to prevent contamination of the intake system such as the air flow meter also to reduce the oil pool in the intercooler & intake piping. Because of the structure of the Nismo Oil Separator it allows for the return of oil from the oil separator to the engine oil pan therefor the consumption of engine oil is decreased reducing the loss of engine oil. In addition the oil separator does not release blow-by gas to the atmosphere so it conforms to regulations as well.