What gauges take over the monitoring of engine oil after engine startup?

The correct answer focuses on the role of the Engine N1 VIB gauges. These gauges monitor engine vibrations, which can indicate the health of the engine during operation. After engine startup, while it's essential to closely observe oil pressure to ensure proper lubrication, the N1 VIB gauges become particularly relevant for ongoing monitoring since they reflect the engine's performance and any vibrations that might suggest issues with the engine's internal components or overall operation.

In the early phases of engine operation, oil pressure indicators show if the oil is circulating correctly, but once the engine is up and running, the N1 VIB gauges provide critical feedback about the engine's operational stability. Monitoring these vibrations helps in identifying any potential problems that could arise as engine components heat up and operate at various RPMs. Thus, while oil pressure is crucial initially, the shift in monitoring focus to engine vibration reflects the evolving dynamics of engine performance once operational.