I really don't drive the car in the rain much (remember it's SoCal weather all year) and there is no salt, other than the ocean. Little need for cosmoline protection. Once the stuff is removed, it's quite easy to pressure wash the underside and then just blow dry. Easy to maintain. Would be nice if the cosmoline just came off with steam cleaning. That would be nice...

 

Cosmoline can be removed professionally with dry ice blasting. No reside to clean up and no damage like media blasting. Google up a video of the process, really neat.