I ride my dirt bikes in Ocala National Forest (think sugar sand) The foam airfilters last about half a day. Then they are clogged with fine sand/dust. I used to use the ultra tacky dirt bike products, which are so tacky, you cannot wash it off your hands or the filter element. Even with strong grease cutting products.
Using gasoline or solvent to clean the filter generally swells up the foam filter, making it useless.
I switched to regular motor oil. What ever I had on hand. Multi grade, straight 30 or 40. Really whatever I had.
I noticed that the carb intake boot/manifold was just as clean with the motor oil as with the dirt bike specific products. In fact, the inside of the filter is also spotless. It is doing it's job.
I understand this is not scientific, however, the motor oil clearly attracts and holds dirt very well.