Filtering consists of a fine mesh stainless steel screen that traps fine oil vapors and releases them once heavy enough to fall. They then pass through a 1/2" thick 1/16th" aluminum honeycomb filter where they grow every larger and then fall into the bottom. By the time the oil gets through the filter it's too heavy to be passed on into the intake. The tank holds 3 oz of fluid, while that may not sound like a lot, you should not see that much oil in your PCV system. Drain it every 5000-7000 miles and you will never come close to filling it.
CA Residents: WARNING: Cancer and Reproductive Harm www.P65Warnings.ca.gov