Before starting a shift, an excavator operator checks the hydraulic oil level using the sight glass. The oil is visible at the very bottom of the indicator, just barely touching the 'add' mark. The excavator has been parked overnight on level ground. What is the appropriate action?

Question: Before starting a shift, an excavator operator checks the hydraulic oil level using the sight glass. The oil is visible at the very bottom of the indicator, just barely touching the 'add' mark. The excavator has been parked overnight on level ground. What is the appropriate action?

Answer options: ✅ Add hydraulic oil immediately until it reaches the middle of the 'full' range.

• Start the machine and warm up the hydraulic system before rechecking the level.
• Continue operations, as it is still within the acceptable minimum.
• Drain all existing hydraulic fluid and replace it with new fluid due to potential contamination.

Correct answer: Add hydraulic oil immediately until it reaches the middle of the 'full' range.

Explanation: If the hydraulic oil is at the 'add' mark or barely touching it, it indicates a low level that requires immediate topping up to the specified operating range (typically the middle of the sight glass when cold and level) to prevent cavitation and damage to the hydraulic system components. (OPSWA Excavator Operator Curriculum, Manufacturer Manuals)