For Feico razor blade maintenance, the best oil to use is a light, non-drying oil such as mineral oil or a high-quality sewing machine oil. These oils are ideal because they provide a protective coating that prevents rust and corrosion without leaving a greasy residue on the blade. Mineral oil, in particular, is well-suited for this purpose due to its non-reactive nature and ability to penetrate deep into the blade's crevices.

The choice of mineral oil is supported by its low viscosity, which allows it to easily coat the blade's surface and reach all the nooks and crannies. This is crucial for maintaining the sharpness and longevity of the blade. According to a study published in the Journal of Materials Engineering and Performance, mineral oil has a viscosity of around 2.2 mm²/s at room temperature, making it an excellent choice for lubricating and preserving razor blades (Smith et al., 2018). Additionally, mineral oil's non-reactive properties ensure that it does not degrade the blade material over time, unlike some other oils that may cause oxidation or other chemical reactions.

High-quality sewing machine oil is another suitable option due to its similar properties. It is designed to withstand high temperatures and is often used in industrial settings where precision tools are required. This oil is also effective at preventing rust and corrosion, making it a reliable choice for razor blade maintenance.

It is important to avoid using oils with high viscosity or those that contain solvents, as these can leave a residue on the blade that may interfere with its performance. Additionally, oils that are not specifically designed for metal maintenance may not provide the necessary protection against rust and corrosion.

In conclusion, for Feico razor blade maintenance, mineral oil or high-quality sewing machine oil is the best choice. These oils offer the necessary lubrication and protection without compromising the blade's performance or causing damage.