Originally Posted By: Garak
Well, that might be a good testing methodology, to trace the source of the dust.
Passed through another possible test site NE of here on the way to Hokkaido by train. Difficult to get my car there though.
Originally Posted By: Garak
Realistically though, outside of agricultural applications, I've never seen an automotive filter that dirty, even with monumental neglect, at least not around here.
Well, my speculation was that it MIGHT not necessarily have to be very (or visibly) dirty for dirt to work its way through. I've no data for this, but its the only justification I can think of for mileage/time limits, where restriction measurements are available.
Come to think of it, are restriction gauges fitted to new cars as OE? ( don't know much about new cars)