I agree a sintered metal filter is much finer, but they can be cleaned. The owner's manual to my 1977 international says to wash the sintered filter on the Hydro-vac brake booster in solvent, then water, then blow dry; once a year.
It is common to see a hd transmission where the range shift cylinder shifts slowly, or not at all. There is a sintered brass filter on the air pressure regulator on the rear of the transmission. I usually wash it with brake cleaner or carb cleaner and blow backwards through it a few times, then rinse it.