Billet dipsticks vent/ breathe excessive crank case pressure from the oil tank through a PVC style breather consisting of an oil separator system, perforated disc, replaceable filter element and umbrella flapper valve. Screws into the factory oil fill spout as a stock replacement part. These breathing dipsticks remove unwanted build-up of blow by pressure, all internal combustion engines have a certain amount of blow by. Larger cubic inch, worn and or loose ring clearance as well as engines pushed to their limits generally have increased blow by. Blow by is pressure that is forced past the rings and cylinders, pushed into the crankcase and then forced back into the oil tank. Dipsticks help remove this unwanted pressure through a (CVS) Crankcase Ventilation System. Feuling test results show a decrease in engine oil sump levels, more freely/ smoother revving engine, increased MPG and decreased blow-by. Dipsticks vent/ breath excessive crank case pressure from the oil tank through a breather system consisting of a oil separator system, perforated disc, replaceable filter element and umbrella flapper valve. Includes two venting styles options to choose from when installing the dipstick. Option 1: 1/8in. NPT breather vent fitting with internal porous filter element (this option gives a clean look, however it can produce an oil misting/ residue out of the element on engines with excessive leakdown/ blow by). Option 2: Quick-disconnect coupler fitting with rubber hose and filter element (this option will run any excessive oil misting/ residue through the line and into the filter element, however this option does requires disconnecting the fitting in order to check the oil. Option 2 is Feulings preferred option as it breaths more than Option 1. For Option 2, Feuling recommends routing the line up the frame rail, up under the seat/ abs area then back down along the right side frame rail and the filter element can fit cleanly between the engine/ trans matting area on the inside of the lower right frame rail. Checking oil level: There a.