ssulb care and cleaning during the winter will definitely help. I know my subframe isn't the greatest and I've thought about replacing it. Since I lowered my car I've had some scrapes and bumps, one incident with summer tires, a freak early snow dusting, and a curb. My subframe is probably structurally sound but as I am building this into a track car I want to have one that's not dinged up and rusted. It'll last the life of the car if all you are doing is commuting but when you start modding requirements can change.