The effectiveness of a can shouldn't really be based on what it catches, but rather what it misses and allows to re-enter the intake. Unfortunately, there really isn't a way to quantify what's missed, but if the outlet hose going back to the manifold is dry, that would be an encouraging sign.

The reason that the amount caught isn't an accurate measure is because the contents of the can primarily consists of (1) actual blow-by product that is successfully condensed and contained by the internals of the can, plus (2) condensation that forms from simple temperature differences as security alluded to several times.

The amount of actual blow-by that passes into the can is affected by vehicle condition, driving habits, oil volatility, environmental conditions. The amount of condensation is also affected by mounting location, can design, can volume, can fill level, filter contamination level, and possibly even hose, union, and connector construction, diameter, length, and routing.

Ultimately, a can that "catches" a lot could just be condensing lots of moisture from the environment. Regardless, if it is letting oil pass through back into the manifold, it doesn't matter how much you find in the can.

Consider this example, where I am exaggerating the amounts to simplify the math: vehicle A produces 10 ounces of blow-by every 10,000 miles and the can successfully contains 4 ounces of it plus 5 ounces of condensation, while vehicle B produces 4 ounces of blow-by and its can successfully contains 3.5 ounces of it plus 1 ounce of condensation... hopefully it's clear which can is doing better. The can on vehicle A contains more fluid, but caught only 40% of blow-by and allowed 6 ounces of blow-by back into the manifold, while the can on vehicle B caught 78% and allowed 1/2 ounce back into the manifold.

 

I am in SoCal and drive about 7,000 mi per year, mostly daily to work and back, which is about 6 miles each way.
I checked the can every 3 ~ 4 months since late 2019 and every time there was about an oz of dark brown oil in it.

 

Thanks for the update. It sounds like you are catching water and blowbye which is to be expected. Which OCC do you have?

 

I am selling my oil catch can. See post #6, $80 plus shipping. Everything you need is included for 2019 RDX, you would just use the OEM hose for the "out" side.
around 15,000 miles since the installation.

 

Did anyone do UOA to compare the results with and without catch can?
does it help with fuel dilution issue?

 

sold