camilla oil works great on surface rust.
https://www.amazon.com/KUROBARA-Tsubaki-Japanese-Maintenance-Camellia/dp/B001TPFVHC/ref=sr_1_8?crid=3ANWUXBGLGVPV&keywords=camilla+oil+japanese&qid=1574446406&sprefix=camilla+oil%2Caps%2C462&sr=8-8
