Hello! There are several rusty spots in the underbody of my vehicle (see photos for examples). What is the best way to do this? And what do you do in these places where this putty (or glue?) is cracked or goes off? At home in my closet, I have body glue, fertan, underbody spray, fluid film and perma film. Is something useful or would you recommend something else? Would you like to have as little work as possible, but rest longer. Thank you for your answers!