There's no oil yet. I was all set to spray it when I thought I might get rid of the rust first.
Again, I'm talking about the *inside* of the frame, not the outside. POR15 won't work as, in my experience, it requires a very thorough prep job, which is impossible to do inside.
I'll be sanding and painting epoxy primer for the *outside*. The first photo shows my first attempt at sandblasting parts of the frame. Works great, but no way to do that for the inside.