How many kilometers should a car drive before needing carbon deposit cleaning?
2 Answers
Cars driving in urban areas are recommended to have carbon deposits cleaned every 20,000 kilometers, while cars frequently driving on highways can have it cleaned every 30,000 to 40,000 kilometers. Engine carbon deposits: Engine carbon deposits refer to a coking-like substance produced by unsaturated olefins and gums in fuel under high-temperature conditions during engine operation. Types of carbon deposits: Carbon deposits can be divided into two types: valve and combustion chamber deposits, and intake pipe deposits. Valve and combustion chamber deposits: Due to the control characteristics of electronic fuel injection engines, each time a cylinder operates, fuel is injected first and then ignited. When the engine is turned off, the ignition is immediately cut off, but the fuel injected during this cycle cannot be recovered and can only adhere to the intake valve and combustion chamber walls. The fuel evaporates easily, but the wax and gum substances in the fuel accumulate over time. With repeated heating, these substances harden and form carbon deposits. Intake pipe deposits: Since the pistons in an engine do not operate synchronously, when the engine is turned off, some cylinders' intake valves may not fully close. Unburned fuel continuously evaporates and oxidizes, forming softer black carbon deposits in the intake pipe, especially behind the throttle valve.
There's actually no fixed mileage interval for carbon deposit cleaning in cars. When I drove an older car, I found that checking it every 25,000 kilometers was about right, but it really depends on your driving habits. If you're always stuck in city traffic doing short trips or using low-quality gasoline, carbon builds up faster, and you might notice sluggish acceleration and soaring fuel consumption after just 15,000 kilometers. If you experience these symptoms, it's best to visit a repair shop or dealership early for an intake system cleaning or fuel injector cleaning—this can save you a lot on fuel costs and avoid major repairs down the line. Regular maintenance with proper fuel additives and weekly highway driving at higher RPMs also helps clear carbon deposits. In short, don't wait until serious problems arise. Regular checks are the most reliable way to prevent issues and extend engine life.
