My manual recommends engine oil on the pre-cleaner if I remember correctly. For exactly that reason - to better trap dust and debris
Here is what the engine manual says for the Kawasaki FS730V on the ZTXS5 54 regarding service of the air filter:
26 MAINTENANCE
Foam Element
Clean the foam element (A) every 25 hours.
• Wash the element in detergent and water, and dry
it thoroughly.
Paper Element
Clean the paper element (B) every 100 hours.
• Clean the paper element by tapping gently to re-
move dust. If very dirty, replace the paper element
with a new one.
Replace with a new paper element yearly or 200
hours. Whichever comes first.
NOTE
○Operating in dusty condition may require more fre-
quent maintenance than above.
CAUTION
Do not wash paper element.
Do not oil foam or paper element.
Do not use pressurized air to clean paper el-
ement.
For engine oil, it gives the usual chart with the arrows, showing SAE40, SAE30, 10w-40, 1w-30 and 5w-20 depending on expected ambient temperature.