Rear Brake Squeal on 2008 Nissan Titan

Purchase 08 with 18,000 first trip began hearing rear brake squeal when you are moving a slow speeds. Now have 34,000 and problem is getting worse. Pads look very good (metallic)
rotors are smooth and look good. I beleive rotors are warped both dealers I have been to tell me this is normal because of oxidation on disc. I do not see any oxidation live in Wyoming and not sure how oxidation occurs at below freezing temps. I beleive it is the rotors and wanted to know what to buy if replacing them. Cannot beleive anyone would want a Titan after they hear my truck roll by and hear the squealing brakes that sounds like your rear end is falling apart.

Asked by for the 2008 Nissan Titan