The best oil for lock lubrication in the United States is typically a high-quality, synthetic oil designed for extreme pressure and high-temperature applications. This type of oil, often referred to as a lithium-based or molybdenum disulfide (moly) grease, provides excellent performance in both dry and wet conditions. It is highly resistant to water washout, which is crucial for maintaining lubrication in outdoor environments and in areas where locks may be exposed to moisture.

The choice of synthetic oil over traditional petroleum-based oils is primarily due to its superior performance characteristics. Synthetic oils have a higher viscosity index, meaning they maintain their lubricating properties over a wider temperature range. This is particularly important for locks, which can experience significant temperature fluctuations, especially in areas with extreme climates. According to a study by the National Lubricating Grease Institute (NLGI), synthetic oils can maintain their effectiveness at temperatures ranging from -40°F to 400°F, making them ideal for a wide range of environments.

Additionally, synthetic oils are less likely to attract dirt and grime, which can lead to wear and tear on lock mechanisms. This is a significant advantage over traditional oils, which can become gummy and attract contaminants over time. The NLGI also notes that synthetic oils can extend the life of lock mechanisms by reducing friction and wear, leading to fewer repairs and replacements.

In conclusion, the use of a high-quality synthetic oil, such as a lithium-based or moly grease, is the best choice for lock lubrication in the United States. Its ability to withstand extreme temperatures, resist water washout, and maintain its lubricating properties over time makes it an ideal choice for ensuring the longevity and reliability of lock mechanisms.