A dump truck's operator manual specifies a coolant concentration of 50% ethylene glycol for freeze protection down to -37°C. During a pre-trip inspection in winter, your hydrometer reading indicates a 30% concentration. What is the most appropriate action in a remote northern B.C. worksite?

Question: A dump truck's operator manual specifies a coolant concentration of 50% ethylene glycol for freeze protection down to -37°C. During a pre-trip inspection in winter, your hydrometer reading indicates a 30% concentration. What is the most appropriate action in a remote northern B.C. worksite?

Answer options:

• Top up with plain water, as only a small amount is missing. ✅ Drain a portion of the coolant and add concentrated antifreeze to achieve the correct ratio.
• Start the engine and let it warm up, then re-check the concentration.
• Continue operation, as -37°C protection is generally sufficient for most winter conditions.

Correct answer: Drain a portion of the coolant and add concentrated antifreeze to achieve the correct ratio.

Explanation: A low concentration compromises freeze protection, risking engine damage. Draining some coolant and adding concentrated antifreeze is necessary to restore the correct ratio and ensure adequate freeze protection without overfilling. (Manufacturer guidelines for coolant systems)