I plan on painting the perches again soon, since it is in the 80's here.
My DH has used motor oil that he needs to get rid of, so I'll use that. I only put it on the bottom of the roost so it doesn't get on the chickens feet. I used the permethrin powder on the rest of the perch. So far, so...
We just use used motor oil and paint it on the bottom of the roosts.
Some people thin the used motor oil with kerosene, or Linseed oil thinned with kerosene.
If you are using it for roost mites, you can also try dusting with Permethrin (spelling?). That is what finally worked for us last...