What should be monitored closely to avoid engine overheating?

Monitoring the coolant level is crucial in preventing engine overheating because coolant is responsible for absorbing heat from the engine and dissipating it through the radiator. If the coolant level is too low, it can lead to inefficient heat transfer, causing the engine temperature to rise beyond safe limits.

Maintaining an adequate coolant level ensures that the engine operates within its optimal temperature range, thereby preventing potential damage from overheating, which can lead to serious mechanical issues such as warped cylinder heads or blown head gaskets.

While factors like oil viscosity and fuel pressure are important for overall engine performance and efficiency, and exhaust emissions can indicate engine health, they do not directly influence the cooling system's ability to prevent overheating in the same way that coolant levels do.