If saltwater leaks into and contaminates the main lubricating oil system, which of the following remedial actions should be taken?

Correct Answer: Option C — Seal off the leak and promptly remove and replace all contaminated oil from the system.

Saltwater contamination in lube oil accelerates severe bearing corrosion, white metal degradation, and abrasive wear. Under marine engineering standards, prompt isolation of the saltwater ingress source followed by complete system draining, flushing, and oil replacement is mandatory to prevent catastrophic turbine failure.