What could indicate that coolant levels are low?

The indication of low coolant levels is most effectively signaled by a fluctuating temperature gauge or the illumination of a warning light. When the coolant levels drop, the engine may not be adequately cooled, which can cause the temperature gauge to rise above normal operating levels. This fluctuation in temperature is a direct response to changes in the ability of the coolant to absorb and dissipate heat. Additionally, warning lights are designed to alert the driver to critical issues, including low coolant levels, providing a clear signal that immediate attention to the engine's cooling system is necessary.

In contrast, constant engine noise typically relates to issues with engine components rather than the cooling system specifically. Changes in exhaust color may indicate various engine malfunctions like fuel mixture problems but do not directly correlate to coolant levels. Unusual tire wear is generally attributed to wheel alignment or suspension issues and is not connected to the cooling system's performance.