I noticed several of the telephone poles running through the ranches I hunt were almost getting worn through. The hogs were rubbing up on them scratching themselves and coating themselves with the creosote to keep the bugs off.
So we started putting diesel soaked post by our feeders, pig pipes, and pig holes. After some experimenting we found the hogs preferred the post soaked in old motor oil. There are times when the hogs will totally bypass they bait but use the rubbing poles.
This one below is just a soaked landscape post next to a pig hole. You cant see it but there is soured corn and scraps buried three ft deep right by the post. They have barely touched the bait but hit the post almost daily in the warmer months.
And here is a tree near one of their bedding areas. They seem to like the sap from pine trees.