How often should carbon deposits inside the engine be cleaned?
3 Answers
Engine internal carbon deposit cleaning intervals vary depending on different conditions: 1. Clean every 15,000km for city driving; 2. Clean every 30,000km for highway driving. The causes of carbon deposit formation are: A coking-like substance produced by unsaturated olefins and colloids in fuel under high temperature conditions during engine operation. Methods to reduce engine internal carbon deposits include: 1. Avoid prolonged idling, low-speed driving, and extended warm-up periods; 2. Do not shift gears at low RPM; 3. Clean the throttle body every 20,000km; 4. Do not stomp on the accelerator while depressing the clutch.
Having driven for over a decade, I've found there's no fixed interval for engine carbon cleaning. If you frequently encounter city traffic jams, cleaning every 20,000 km is advisable—especially for vehicles making short round trips where the engine doesn't fully warm up before shutting off, as carbon buildup occurs easily. For highway-heavy driving with more complete combustion, you can delay maintenance to 30,000–40,000 km. Last time my car had weak acceleration and vibration, the mechanic found carbon sludge coating the valves. Now I regularly add quality fuel system cleaner and ask technicians to inspect the intake manifold during servicing to prevent fuel efficiency and power loss. Avoiding prolonged idling is also crucial in daily driving.
Our fleet drivers often talk about carbon buildup issues during chats. Direct injection vehicles require extra attention, with carbon deposits needing inspection every 20,000 kilometers. Last time I drove that turbocharged car, it made clicking noises during cold starts - half the fuel injectors were clogged. I've learned my lesson now: adding OEM cleaner every 10,000 km and performing thorough cleaning at 30,000 km intervals. Aggressive driving habits might help, but vehicles used for school runs with constant low-speed crawling accumulate throttle body deposits rapidly. While following maintenance manual recommendations, I suggest everyone monitor exhaust pipes for black soot or sudden fuel consumption increases.