What routine maintenance should be performed on a micrometer?

Routine maintenance on a micrometer is essential to ensure its accuracy and longevity. Regularly wiping the spindle and applying a small amount of multipurpose oil helps to keep the measurement surfaces clean and free from rust and debris, which can affect performance. Proper lubrication prevents wear on the moving parts, ensuring smoother operation over time.

Avoiding humid storage is important because moisture can lead to corrosion and damage to the precision measuring tools. Humid conditions can allow rust to form on the metal components of a micrometer, compromising its accuracy.

Each aspect of the correct answer focuses on maintaining the tool in optimal condition, making it suitable for precise measurements. Proper storage that minimizes exposure to humidity, along with regular cleaning and lubrication, directly contributes to maintaining the tool's calibration and functionality.