Let's start with the basics: How does the start-stop system actually work?

The start-stop system in modern vehicles like BMW, Audi, or the Ford Focus plays an important role in reducing fuel consumption. The system works by automatically shutting off the engine when the vehicle comes to a stop, such as at a traffic light, and restarting it as soon as the driver presses the clutch or releases the brake. This system helps reduce fuel consumption and protect the environment from harmful emissions.

It doesn't damage the engine!

Opponents of such technical innovations often argue that the start-stop function surely affects the condition of the engine.

However, these concerns are exaggerated. Automakers are well aware of which parts of the engine are subjected to stress and simply make them more robust. A good example of this is the starter, which has to perform many more work cycles in vehicles with a start-stop system than in those without it. Therefore, start-stop engines are equipped with a more powerful, durable starter that not only withstands more intensive use but also enables the engine to start instantly.

And what about the turbocharger? Automakers have considered that too. The computer that controls the engine is programmed to monitor the engine's condition: its temperature, oil pressure, battery charge level, or energy demand.

If shutting off the engine at a particular moment could cause damage to the turbocharger, the system simply won’t turn off the engine. This is why the system may not operate under certain conditions: when the engine temperature is too low and the oil is not functioning optimally, or when the power consumption of audio systems, air conditioning, and other devices is so high that the battery risks being drained. The start-stop system can also keep the coolant or oil pumps running while the engine is off, so there are no issues with lubrication or engine temperature upon restarting.

Greater Capacity

To stop and start the engine multiple times in succession, an appropriate voltage is required, which must always be available to ensure that the car does not stall in the middle of the road. Therefore, cars equipped with this system have batteries with greater capacity. It is important that these batteries can withstand rapid discharges and charges. For many drivers, this is another argument against the start-stop system. However, in cars equipped with electronics and numerous entertainment, navigation, or audio systems, such batteries will sooner or later become the norm, regardless of the start-stop system.

Significant Reduction in Emissions

Skeptics also claim that the start-stop system does not significantly reduce fuel consumption or CO2 emissions. The average user indeed notices only minimal benefits in this regard. It is no secret that these systems were introduced to reduce global consumption and emissions and to enable automakers to comply with the latest regulations. Even if it doesn't make a significant difference for us to save even 1 liter of fuel over 100 kilometers, a considerable result is achieved when we multiply this by the tens of millions of new cars sold annually; the same applies to CO2 emissions.

What About the Engine Oil?

The start-stop system presents a serious challenge for engine oil. Oil can most effectively perform its task under certain conditions, which are difficult to achieve with the constant starting and stopping of the engine.

Therefore, manufacturers use additional components that improve flow properties:

"During the warm-up phase, we are dealing with high viscosity. It is true that the engine will not be turned off when stopping until a certain temperature is reached, but it should not be forgotten that the oil does not warm up as quickly as the coolant, and even after several kilometers, it does not reach its optimal operating temperature. To solve the problem of high viscosity, high-quality base oils and viscosity modifiers are used. As a result, we achieve oils with high-temperature stability. Such oils remain liquid even under severe frost conditions.

Viscosity modifiers are also necessary at high temperatures. In the turbocharger, for example, they ensure that a thick, durable oil layer is maintained. To prevent the thermal degradation of the oil, we use antioxidants that prevent the oxidation and aging of the oil.

Due to the frequent shutdown of the engine, the oil flows back into the oil pan as well. If these unfavorable conditions persist even for a few minutes, it can lead to the loss of the oil layer. This is where Magnatec Dualock technology comes into play, which, with the help of friction modifiers and active molecules, provides appropriate protection for the engine," explains Paweł Mastalerek from Castrol's technical department.

What Disadvantages Could Start-Stop Systems Have?

Start-stop systems in cars can have some disadvantages. They can increase the wear of certain components, as these are more heavily stressed by the frequent starting and stopping of the engine. Additionally, the system may be perceived as annoying, as there may be delays in restarting the engine, especially in city traffic. The additional load on the battery, which must power many electrical consumers while stationary, can also shorten its lifespan.

How Can This System Be Permanently Disabled?

The start-stop system can be manually disabled at the beginning of each journey by pressing a designated button. However, please note that this must be done every time the vehicle is started, as it is not permanently saved.

Alternatively, the system can be permanently disabled by reprogramming the control unit or using aftermarket devices, which requires professional assistance and could potentially affect the vehicle's warranty. Errors during the reprogramming process can lead to issues and may affect the vehicle's warranty.