I have used a thin coating of 3-in-1 oil on bare metal parts that I am not ready to prime. Seems to work well in the Houston area. Just have to be sure to get it all off before spraying.
I also used some rust disolver from Home Depot on my hood. The results are very good although it took several applications. The metal has not re-rusted as yet as it seems to have left a film on the metal. To remove it will take a DA sander or a wire wheel.