In which situation would you check the steering fluid level?

Checking the steering fluid level is crucial when there is a whining noise coming from the steering system. This sound often indicates that the fluid level may be low, which can compromise the power steering system's ability to function properly. Low fluid can lead to air entering the system, resulting in both the noisy operation and potential damage to the components, such as the power steering pump. By checking the fluid level in this scenario, a mechanic can determine if a refill is necessary or if there's a deeper issue that needs to be addressed, such as a leak in the system.

In contrast, checking the steering fluid level after tire rotation, after an oil change, or when the vehicle is cold is generally not indicated as these activities do not typically affect the steering system directly. Tire rotation and oil changes focus on other aspects of vehicle maintenance, while a cold engine temperature may not provide an accurate reading of the steering fluid level due to its viscosity when cold. Therefore, the optimal time to check the steering fluid is during instances of operational issues such as unusual noises.