FAA Powerplant Written Practice Test

Compared to reciprocating engine oils, what is a characteristic of oils used in turbine engines?

1. They produce more lacquer

2. They produce more coke

3. They have less tendency to produce lacquer or coke

4. They have a shorter lifespan

The correct answer is: They have less tendency to produce lacquer or coke

Oils used in turbine engines are formulated specifically to meet the demands of high-temperature and high-speed operations. One of the key characteristics of these oils is their refined formulation, which results in a significantly reduced tendency to produce lacquer or coke compared to oils used in reciprocating engines. Reciprocating engine oils can break down under high temperatures and stress, leading to deposits like lacquer and coke that can contaminate the engine and reduce its efficiency. In contrast, turbine engine oils are designed to maintain their stability at elevated temperatures, preventing the formation of harmful deposits. This is crucial for ensuring the reliability and longevity of turbine engines, which operate under conditions that can lead to much higher thermal and oxidative stresses. Thus, the formulation of turbine engine oils allows for cleaner operation by minimizing the buildup of such detrimental byproducts, enhancing performance and reducing maintenance issues associated with deposits in the engine.