Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What is a common characteristic of lubricants with high viscosity?

1. They increase energy efficiency

2. They flow easily

3. They provide better lubrication in high temperatures

4. They resist thinning under stress

The correct answer is: They resist thinning under stress

Lubricants with high viscosity are characterized by their ability to resist thinning when subjected to mechanical stress or shear forces. This property is crucial in applications where equipment operates under heavy loads or high temperatures. High-viscosity lubricants maintain their thickness, providing a consistent lubrication layer that protects the machinery and reduces wear and tear over time. This resistance to thinning ensures that the lubricant is effective in preventing metal-to-metal contact, which can lead to increased friction, heat, and ultimately, failure of the components being lubricated. While other choices may seem relevant to lubrication in general, they do not accurately represent the defining trait of high-viscosity lubricants. For instance, while a lubricant can contribute to energy efficiency, this is not inherently related to its viscosity. Similarly, the ease of flow is characteristic of low-viscosity lubricants rather than high viscosity. Finally, although some lubricants may perform better at higher temperatures, this is not a universal trait of all high-viscosity lubricants. Therefore, the key characteristic that defines high-viscosity lubricants is their resistance to thinning under stress.