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Why Is Sitting In Traffic Bad For Cars?

Dealing with traffic is universally loathed – the frustration, environmental toll, and potential for road rage make it an unpleasant experience. However, there's an aspect of this automotive inconvenience that often goes unnoticed: its detrimental impact on your vehicle.

Now, before the scepticism kicks in, let's address the obvious question: How can traffic be harmful to my car when it's precisely what it was designed for?

Here's the catch. While modern cars are somewhat engineered to navigate through traffic, it remains one of the harshest conditions for an engine. Let's delve into the specifics.

Firstly, consider an engine as a massive hot air pump. As pistons move, they generate heat and kinetic energy, with the latter being transformed into rotational energy that propels the wheels. While kinetic energy is essential, heat energy poses a challenge.

Many might not realize that the thermal efficiency of a petrol or diesel engine is shockingly low, with up to 50% of the potential energy in fuel lost as heat. Essentially, the engine functions as a giant heat sink that needs to maintain a constant temperature to safeguard components, seals, and fluids.

A vehicle moving along the road naturally channels air through a radiator for cooling. However, in standstill traffic, this cooling effect diminishes. Cooling fans are employed to replicate airflow, but they can struggle to keep the engine and oil within the preferred temperature range, affecting lubrication and longevity.

For example, while the running temperature may be 95°C and the oil breakdown temperature might begin at 105°C, a car idling in traffic might sit closer to 102°C. Running an oil past its operating window can greatly reduce the lifespan and mean it's not able to do the job of lubricating the engine.

Another crucial principle, volumetric efficiency, comes into play. Engines operate optimally at specific RPM points, usually at full throttle. Prolonged idling makes the engine less efficient and challenges emission control. Fine-tuning fuel injection values in modern cars helps, but there's always room for improvement.

EGRs and DPFs, designed to reduce emissions, can lead to issues. EGRs cause carbon build-up, reducing performance, and DPFs may clog with diesel soot. Continuous idling also significantly increases the risk of cylinder glazing.

This references a condition where the cylinder surface becomes "damaged". In fact, glazed cylinders can lead to high oil use, worse economy and lower power outputs as the surface finish allows fuel or oil to bypass the piston.

The most significant concern is the argument of running time vs. kilometres travelled. Unlike servicing in stationary equipment which is based on hours of running time, cars are traditionally serviced by kilometres travelled. However, at idle, the engine and engine oil still experiences significant wear and tear.

To combat this problem for cars in heavily trafficked countries, many manufacturers have reduced the service intervals from every six months to every three.

In essence, traffic is bad for cars as they produce higher levels of emissions, can suffer higher wear and tear, and can (occasionally) infer long-term damage. The ideal solution? Aside from reducing traffic or minimizing your vehicle's time in it, regular servicing remains the best preventive measure against excess wear and tear.


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