Checked my records on this last oil swap and cleaned the stock foam filter after 1500 kms (900 miles). Probably should cleaned it sooner however due to snorkel intake, just below cab roof was pretty clean. Dawn soap to clean in hot water, lightly squeeze most water out with paper towel, air dry overnight. Oil and reinstall. Order an extra new stock one from dealership. Have tried K&N on lotsa small normally aspirated engines and they work if maintained. Forced induction like my 7.3 Power stroke not a chance..... down that path once, Donaldson large paper element that gets tossed every second oil change. K&N in 7.3 application 9” diameter by 11” long round didn’t filter well enough to keep out finds. Now this was with bigger injectors, turbo and buncha modes. Replaced with same size Donaldson... not anything in the intake.
As a good tell tale use a clean white fine woven cloth, wipe out the intake post filter and see how much keerap you pick up. The above paper filter looks like a nice option if you are in severe dusty conditions, just have to mess with crank breather tube, could be fashioned like K&N.
I’ll use stock for now..