didn't let the ash thru cuz the particles stay in the oil, oil bath filters don't plug up until the oil turns to grease
your reasoning Tiny, is the common take on the question, but on a vehicle subject to dusty conditions
they\'re best if properly maintained - apparently
the SAE agrees the reason the switch was made is most city vehicle use doesn't warrant the extra expense in manufacturing and the OEM's cut every corner they can
Bill