D'oh! I have the day off and just spent 2 hours handwashing/detailing my truck. We've had record snow this year, along with record salt treatments, and I hadn't washed it since December. Well, lo and behold I had a LOT of surface rust on the sides of my rear bumper. So much that I thought it wasn't just surface rust. There was more rust than chrome on the left and right bumper faces that sit behind the rear fenders. Back to the dealer, I thought.
Then I remembered something. Being a shooter, I have a tube of JB Bore Paste on hand. It's basically a very mild polish we use when we want to get a rifle bore really clean.
Holy cow. I used about as much paste on one side as you would toothpaste for a brushing, and then rubbed it around with a paper towel. Literally, the rust disappeared instantly. I followed up with some Flitz chrome polish spray and it's good as new!! Took me all of 5 minutes, and saved me a trip to the dealer.
Now I know some people are going to say that rust can't be killed, and once it starts it won't stop. I'll keep an eye on it, but for now it looks showroom new and it took all of 5 minutes.
For those of you who don't have JB around, a tube of Flitz metal polish would be similar (maybe slightly more aggressive). Go a little light if you try Flitz, but it should work just as well. You can get JB from any big online gunstore. And you can get a tube of Flitz at any hardware store for about 5 bucks. Hope it helps someone! Wish I would have taken before-photos, but I didn't think it would work, much less work so amazingly well!