Feuling Vented Dipsticks
Designed to screw into the factory oil fill spout as a stock replacement part, these vented dipsticks from Oceanside, California based Feuling Parts can "save a whole world of hurt," according to CEO Luke Leatherman.
"These are breathing dipsticks and they remove unwanted build-up of the blow-by which is found in engines with excessive leakdown through the rings/cylinders - a common issue with large displacement big bore engines.
"Our test results show a decrease in engine oil sump levels, a more freely and smoother revving engine, increased MPG and decreased blow-by. They vent excessive pressure from the oil tank through a breather system consisting of a filter element and umbrella valve."
Feuling offers two venting style options when installing this dipstick.
Option 1 is to use the 1/8" 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 is to use a 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, but does require disconnecting the fitting in order to check the oil.
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.
There are two ways to read the oil level with this dipstick - with the bike on the jiffy stand (FHS) or the bike upright and level (FHU).
If reading the dipstick with the bike on the jiffy stand, the reading is taken from the dimples labeled FHS (Full Hot Stand); when reading with the bike upright and level, the reading is taken from the FHU (Full Hot Upright) labeled dimples.
Available in polished or fade-resistant black for '06 and up Twin Cam or '07 and up FL models, these dipsticks do get hot, so use a glove when checking the oil level. Feuling highly recommends staying off the rev limiter and running conventional oil in M-8 engines to help maintain ring seal and minimize blow-by.
Because it is important to get the correct hot oil level, Feuling recommends running the oil level 90%-99% full when hot. "One thing to bear in mind - because the oil pick-up port is on the right side of the engine, letting the bike idle or warm up on the kickstand will naturally fill the engine case and skew the oil level in the tank."