Windshield frame rust treatment/prevention

[zac]

My new truck has just a tiny bit of rust up there, in the corner on the far left. There's actually just a little crack with some rust around it. I could kind of reach my finger in there through the visor mounting hole. Nothing serious, but I'm paranoid after what happened to the frame on my old truck. I read in "Vintage Truck" magazine some guy drilled holes through the inside of his frame, fogged some used oil in there once a year, and stuck plugs in the holes. So that ain't gonna happen. Any other ideas of what I could spray in there other than plain old Rustoleum?