Must be the salt on the roads (we don't do that here). I use Finish Line's wet lube (thick stuff) and my chain is usually good for a couple weeks of wet riding. It's a sloppy, greasy mess to touch, but it stays quiet and doesn't rust. Usually I end up wanting to clean the drivetrain because of build-up on the derailleur pulleys before it gets to the point where I think it needs lube.