Performance Air Filters for a W9 with Cat motor.

I always just put a new air filter in annually. And that would be anywhere from about 45,000-75,000 miles on the odometer at that point. It could probably go another year because it never looks real dirty because I'm all highway miles. Now someone pulling a hopper and/or off road in extremely dusty situations that might be too long to go before swapping in a new one.

Yeah just that one sample and right after a rebuild don't sweat it. It'll most likely be down to normal the next time. It probably flagged it yellow on your SOS report and said to "sample as usual and run as normal, see what it says next time" or should have said that. Next time it'll probably be green. I did CAT SOS on every 12,500 oil change for the last several years of owning that other cat powered truck. I got a couple of bad samples that worried me but turned out to be nothing by the next sample. It happens but in your case dirt, or I should say dust, got inside of that engine while it was being rebuilt. Which happens to every engine that gets inframed.