Goglio704 wrote:
I have seen and used filters which remove oil from compressed air. They are pretty much a must before a dessicant air dryer. Is that what you are thinking of from McMaster or MSC? I am not dismissing the idea, but these filters are designed to run at much higher pressure (100 to 120 PSI). If they need even a small amount of differential pressure across them to work, they aren't going to work as a crank vent filter. I don't know how much differential they need, I'm just saying if they need much - it ain't there. It would be worth looking into, but we would need some numbers about crankcase pressure on the CRD. I can't speak for Old Navy, but I think the intent of his project is to make something that is purpose built for the application. Something that looks like it belongs there and doesn't eat up underhood space, which is already minimal.
Regarding the pressure required to flow through an air-compressor filter: I can't say for sure. What I can say is that many of us are running them with no problems and they do catch a lot of oil. Look here:
http://www.pbase.com/rsrock/oil_catch_can
And like I said you can purchase these components most anywhere; even Home Depot. I will point out though that the glass units can occasionally experience shattering. Since water vapor accumulates in there also; if you collect enough water it can freeze and shatter. I've only heard of this happening on one occasion though.