I usually use Mothers Back to Black. For me, it works good for weeks. Somethimes I use WD40. Never had a problem, and neither really attracts dust anymore than bare plastic. And when I am too lazy, I use Meguiars Endurance on the air dam on my GMC.
FYI - WD40 or a good tire shine (such as Meguiars Endurance) are the absolute best for textured semi flat powdercoat.



