If oil temperature exceeds 140°C, how long, in minutes, is operation up to 155°C permitted?

• A. 30
• B. 60
• C. 15
• D. 45

Answer: (D)

When oil temperature climbs into elevated ranges, the operating limits allow a finite amount of time to remain in that higher band. This is to protect the oil from accelerated degradation and maintain lubrication quality.

In this case, once oil temperature exceeds 140°C, you’re permitted to operate up to 155°C for a maximum of 45 minutes. This provides a safe window to continue mission-critical actions or transit while the oil temp rises, but it must be cooled or the system taken out of service if you approach or reach 155°C for longer than the allowed time.

That’s why 45 minutes is the correct duration. Shorter times (like 15 or 30 minutes) would be unnecessarily restrictive, and a longer time (60 minutes) would exceed the documented limit for this temperature band.