The SS oil filter manufactured by Scotts performance products over here in the states filters to 35 microns absolute. That means that no particles larger than 35 microns can pass.
Paper filters filter down to about 13 microns, BUT, it's not absolute. Meaning that they will pass particles as large as 100 microns.
Also, on cold start up when the oil is it's most viscous, especially when there is low outside temps, paper filters will not flow enough oil, so the by-pass opens and unfiltered oil is used until the oil comes up to temp, becomes "thinner" and the by pass closes and oil resumes it's normal journey through the oil filter. It also needs to be mentioned that a SS filters flows more oil than a paper filter, even when it's pretty full. Ever tried to pour oil through a paper towl, or a coffee filter??
A very good mechanic I know has told me that he has seen motors, specifically the inside, that have used the SS filters and are covered in a thin layer of very fine metal particles.
HOWEVER, I HAVE BEEN USING A SS OIL FILTER FOR THE LAST 6 YEARS, AND WILL CONTINUE TO DO SO. I do think in the future that I might put a paper unit in every once and a while for one interval and then disect it to see what comes out.
As far as cleaning, drying etc... I use a CRC product called Lectra-Solv. An electrical motor cleaning solvent in an aerosol can, it's about $3.50 USD. I usually use a whole can spraying from the inside out, going down each row facing down with the straw stuck inside the filter blowing out into a very clean drain pan so that I can see what comes out. Don't use all the cleaner at once, make a good pass all the way around. Then I use an opti visor in bright light like the sun, to make a visual inspection of the outside. I will usually find an area that I missed and hit it again. I then set my air pressure regulator to about 20psi, and use and air hose to blow it out, from the INSIDE out to dry it.
This practice has worked very well for me, and when I have taken my motor in to be torn down, to the mechanic I mentioned above, he has never mentioned to me that my motor was covered in this fine metal particulate. My personal opinion about the motors that are covered with fine metal are that the owners have not been doing proper maintenance in the first place.
Moral of the story, no matter what filter you use, change the oil frequently and your motor will be happy.
