FAA Powerplant Written Practice Test

What is a characteristic of ashless-dispersant oil?

1. It contains no minerals

2. It minimizes carbon deposits

3. It thickens at high temperatures

4. It is only suited for aviation-grade engines

The correct answer is: It minimizes carbon deposits

Ashless-dispersant oil is specially formulated to enhance engine performance by minimizing carbon deposits. One of its key characteristics is that it contains additives that help keep contaminants suspended in the oil, preventing them from settling as sludge or forming deposits on critical engine components. This is particularly important in aviation engines, where optimal performance and reliability are crucial. By controlling the formation of deposits, ashless-dispersant oils contribute to cleaner engine operation, reduced maintenance, and improved longevity of engine components. While it's true that these oils may not contain mineral additives, their distinct feature lies in their ability to manage carbon and other particulates, making the ability to minimize carbon deposits the defining attribute. The other choices relate to attributes that either do not specifically pertain to ashless-dispersant oils or are more general characteristics that do not encapsulate the unique advantages these oils provide in terms of deposit control.