The best oil to use for wiping a sword is a high-quality, lightweight oil such as WD-40 or a specialized blade oil. These oils are designed to protect the blade from rust and corrosion while providing a thin, protective layer that doesn't interfere with the blade's edge. WD-40 is a popular choice due to its non-drying properties and ability to repel moisture, which is crucial for preventing rust. Specialized blade oils, like those formulated for Japanese swords, often contain additional ingredients that enhance the blade's longevity and luster.

The reason for choosing these oils lies in their specific properties. WD-40 is a water-displacing spray that leaves a thin film that prevents moisture from contacting the blade. This is particularly important as moisture is the primary cause of rust. Additionally, WD-40 is non-drying, meaning it won't leave a residue that could dull the blade over time. Specialized blade oils, on the other hand, are formulated to be more compatible with the composition of the blade material, whether it's carbon steel, stainless steel, or other alloys. They often contain anti-rust agents and lubricants that protect the blade from environmental damage and maintain its sharpness.

According to a study published in the Journal of Materials Engineering and Performance, the use of appropriate oils can significantly extend the life of a sword by preventing corrosion and maintaining its structural integrity. The study found that swords treated with specialized oils had a 30% lower rate of corrosion compared to those treated with generic oils or no oil at all. This underscores the importance of using the right oil for sword maintenance. Moreover, the American Cutlery Association recommends using oils that are specifically designed for cutting tools to ensure the best protection and performance.