Canadian Council of Independent Laboratories (CCIL) Practice Exam 2025 - Free CCIL Practice Questions and Study Guide

The recommendation to use petroleum-based oil for lubricating the curved surface of a socket is based on the properties of this type of lubricant. Petroleum-based oils have excellent lubricating qualities, which help reduce friction and wear between the contacting surfaces. They are also generally resistant to breakdown under various operating temperatures and conditions, ensuring a stable performance over time.

Additionally, petroleum-based oils often contain additives that enhance their protective qualities, helping to prevent rust and corrosion, which can be particularly important in mechanical applications. This characteristic makes them suitable for use in a variety of environments where durability and reliability are necessary.

In contrast, other types of oils like synthetic oil, while also effective, are typically reserved for specific applications that require enhanced performance beyond what petroleum oils can provide, and their cost can be higher. Vegetable oils might not provide the same level of lubrication and could potentially degrade faster under heat. Mineral oil, while similar to petroleum oil, usually lacks the additional properties beneficial for more demanding applications. Therefore, petroleum-based oil stands out as the best choice for this particular use in maintaining the functionality of the socket.