My fenders had some surface rust 28 years ago so I gave them a "temporary" coat of Rustoleum. Other spots that popped up rusty were "treated" with gray primer but that doesn't seal out water so I've switched to flat gray spray enamel.
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.