check out this link i am doing it right now
http://handycrowd.hubpages.com/hub/Chicken-Scaly-Leg-Mites
If you will look at that last pic where it's titled "all the scale mites are dead and gone" you can clearly see that they are indeed NOT all dead and gone. Right at the ankle that bird still has raised, thickened scales and will likely get those scale mites right back. Sorry...cooking oil is just not going to cut it when someone has let them get that bad.