Diggndumps, i have never put any oil on them. I clean the insides with copper shot i cut up from copper wire and a little bit of liquid barkeepers friend, or water. On the outside i use a scotch brite plastic scouring pad. Harry Pristis recently commented on how to make your own bottle brush.,if i have a tough inside stain, i use the method he described. The burger was one i made at work yesterday. We like to cook for our employees about once a week. ...i suppose at some point i will have to show some bass pictures. Lol.