The way we drive in our daily lives often subjects a car’s main components to unsuspected challenges, without us even realizing the destructive consequences. Gentle, cautious urban driving over short distances creates a false sense of careful use, while in reality the inside of the engine suffers from a serious lack of thermal load.
During prolonged cycles at low revs and constant stops at traffic lights, combustion processes do not occur with the necessary efficiency, leading to massive deposits of soot and carbon in the cylinders. These carbon deposits appear unnoticed, but over time they begin to negatively affect the vehicle’s overall behavior. The accelerator response becomes sluggish, performance deteriorates, and the powertrain loses its original smoothness and pulling power.
The natural way to deal with this problem is dynamic driving outside the city, where the roads allow a consistently high speed to be maintained, along with overtaking maneuvers. Under these conditions, the temperature in the system rises to an optimal level, lubricants circulate at maximum speed through the engine’s arteries, and newly formed contaminants simply burn away. As a result, the feeling behind the wheel becomes noticeably livelier, and the car’s behavior returns to its normal parameters.
Maintaining consistently excessive revs, however, carries serious risks and is by no means a cure-all. Extreme sporty driving places excessive strain on mechanical components and accelerates the thermal degradation of engine oil, shortening the life of the entire mechanical structure. Instead, experts advise applying measured, controlled load to a fully warmed-up engine, activating its natural cleaning mechanisms without unnecessary risks.
City traffic makes this process extremely difficult to achieve naturally. Modern cars, especially those with automatic transmissions, are programmed to shift into the highest possible gear at the earliest opportunity in order to optimize fuel consumption. This keeps the revs at a minimum for most of the time, depriving the engine of the temperature and load necessary for self-cleaning.
The solution to this technical issue lies in an elegant and proven trick recommended by industry experts
When the car is fully warmed up and traveling on a motorway, it is enough to raise the revs to around 4,500 rpm for the short period of two minutes, without making any sudden or risky maneuvers. Drivers of cars with automatic transmissions can do this by activating sport mode, which holds the gears for longer, or by manually shifting into a lower gear.
This specific technique allows the powertrain to restore its normal operating rhythm while also bringing the catalytic converter up to its optimal temperature. Balance is crucial in this approach, as the procedure is intended only for brief use after full operating temperature has been reached, while consistently aggressive driving remains harmful to the vehicle’s long-term reliability.
Experts clarify that this problem and the corresponding self-cleaning method mainly concern gasoline engines with direct fuel injection, as well as modern diesel powertrains, although the nature of carbon and soot deposits differs between them.
Gasoline engines
In direct-injection powertrains, fuel enters the combustion chamber directly rather than passing over the intake valves, making them particularly susceptible to carbon buildup during constant urban driving at low revs.
Diesel vehicles
Here, low revs in urban conditions lead to rapid clogging not only of the cylinders but also of expensive components such as particulate filters and exhaust gas recirculation systems.
Briefly raising the revs with the engine fully warmed up helps burn off some of these deposits in both types of engines, but diesel powertrains often require longer driving under load outside the city for complete filter regeneration.