This has nothing to do with the good or bad filtration dispute; but cleaning the K&N Air Filter is to much labor for them to be used on any large Vehicle if someone was paying a Mechanic to do the cleaning.

Also the more Filters on some large Equipment can blown out with low pressure Air; washed; dried and reused.
At the last place I worked as a Mechanic I had 2 Filters per Vehicle. The Yard was 40 Acres of dirt and I would swap the Filter as soon as the equipment stopped moving long enough for Me to do so and blow out the one I removed and put it in a plastic Bag.
If it was Hot out and I had enough time I would was the one I removed.

The one piece of Equipment had a $68 outer Air Filter and $50 something inner Filter.
If I replaced them ever Day because they were plugged it would have been very expensive by the end of the Month; and times that by the other equipment Filters.

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84 300D, 82 Volvo 244Gl Diesel