What feature is included in the T-6's oil pressure monitoring system?

The T-6's oil pressure monitoring system is designed to include annunciators for oil pressure. This feature is crucial as it provides pilot alerts regarding the oil pressure status, allowing for real-time monitoring and ensuring that any anomalies can be addressed promptly. Maintaining proper oil pressure is vital for engine health, and the annunciators help the pilot to respond quickly to any potential issues, enhancing safety during flight operations.

In contrast, the other options do not specifically pertain to the oil pressure monitoring system. While a temperature gauge is important for monitoring other aspects of the aircraft, it does not relate directly to oil pressure. A filter status light may provide general information about the engine system's condition but is not specific to oil pressure monitoring. A fuel efficiency monitor focuses on a different aspect of aircraft performance and does not pertain to the oil system. Thus, the presence of annunciators for oil pressure is the defining feature of the T-6's oil pressure monitoring system.