My suggestion is not to be overly concerned w/ the nuts or studs. They get that way because of the eliments and conditions to which they are exposed. They are (carbon steel) because the specified material has the requires tinsel strength to meet the torque and expansion/contraction requirerments. I do NOT reccommend replacement unless you replace 'in-kind' - in which case, the same situation will repeat. What you can do is clean and lube the protruding stud and nut, and possibly cover with a stainless or chrome acorn nut. This will protect the threads, hide the un-shinny metal, comfort your heart, and provide you with countless ours of chrome adiction happiness. Personally, I use a drop of 3-in-1 oil from time to time - I'm not addicted.
