My truck was badly oxidized from sitting for 35 years with no love. I hit it hard with CLR and scotchbrite to clean it up. That took care of the oxidation and surface rust.
I then gave it a really good coat of wax and it looked awesome, for a couple of months. Then every in perfection, crack crevice, etc turned white from the dried wax.
This summer I plan on stripping the wax and giving it a good rub down with some Gibb's oil.
http://www.getgibbs.com/
I have also heard of good things about Boiled Linseed Oil. Rub it on and let it back in the sun. I used it on my bed rails and bed wood and it turned out great.