New Vehicle Limited Warranty
General Motors Corporation will provide for repairs to the vehicle during the warranty period in accordance with the following terms, conditions, and limitations:
What Is Covered
Corrosion: Body sheet metal panels are covered against rust under the Bumper-to-Bumper coverage.
Rust-Through: Any body sheet metal panel that rusts through, an actual hole in the sheet metal, is covered for up to 6 years or 100,000 miles, whichever comes first; 6 years/unlimited miles for Buick, Cadillac, and Saab.
What is not covered:
Damage or Corrosion Due to Environment, Chemical Treatments, or Aftermarket Products
Damage caused by airborne fallout, salt from sea air, salt or other materials used to control road conditions, chemicals, tree sap, stones, hail, earthquake, water or flood, windstorm, lightning, the application of chemicals or sealants subsequent to manufacture, is not covered. See "Chemical Paint Spotting" under Things You Should Know About the New Vehicle Limited Warranty for more details.
So they initially say that they will cover corrosion, then turn around & say that they won't. If I lived in the islands I think I'd be rethinking purchasing a vehicle from GM.