I am thinking mineral oil might work in a pinch if you do not have access to anything else but I also think there are better products on the market that are made especially for the job. The following has been posted before but now might be a good time to review it. My guns cost to much to leave anything to chance. I want the best protection I can get.
The Gun Zone -- Corrosion Test
By faith Noah,being warned of God of things not seen as yet, moved with fear,prepared an ark to the saving of his house;by the which he condemned the world,and became heir of the righteousness which is by faith Heb.11:7