Since you're in LA, you don't have to contend with road salt and all the other corrosives that winter-snow commuters do. Your frame should be fine in the rain. I used to ride my old steel MTBs through creeks and in the rain, etc. without ever having heard of FrameSaver.

Like Andy K, I contend with a lot of rain all winter and he's right. There's no need for an elaborate routine. I keep 2 chains in rotation for the winter and swap them out from a jar of mineral spirits about every 2 weeks. At that time I'll wipe down the rest of the drivetrain and check my brake pads and rims. That's about it.