What are the consequences of prolonged engine speed below 2000 RPM?

[McRuby]

The consequence of prolonged engine speed below 2000 RPM is excessive carbon buildup. It is recommended to drive at higher speeds occasionally for better engine performance. Long-term low-speed driving can cause significant damage to your vehicle for the following reasons: 1. Incomplete combustion - When the engine operates at low RPM for extended periods, its power output remains underutilized, leading to substantial carbon deposits; 2. Increased accident risk - Sustained low-speed driving makes your vehicle vulnerable to sideswiping during overtaking maneuvers, significantly raising accident probability; 3. Higher fuel consumption - Most sedans achieve optimal fuel efficiency at around 90 km/h, with speeds either below or above this range resulting in increased fuel consumption. Therefore, the best practice is to adjust driving patterns appropriately, accurately assess road conditions, and maintain cautious driving habits.

[SanDallas]

Keeping the engine RPM below 2000 for extended periods is not good. I used to drive like this in city traffic jams too, but the mechanic warned me it leads to easier carbon buildup in the engine. When RPM is too low, gasoline doesn't burn completely, and excessive carbon deposits can make the car lose power and become more fuel-consuming. Last time, my car shook like a massage chair because of this, and I ended up spending hundreds to clean the throttle body. What's worse, the transmission suffers too—especially automatic transmissions that frequently shift gears can easily overheat. I've heard occasionally driving on the highway at higher RPMs can actually help clean carbon deposits. Now when I hit the highway, I specifically switch to manual mode and rev up to 4000 RPM for a few minutes.

[DallasMarie]

Back when I drove a taxi, I saw many experienced drivers always keeping the RPM too low. When the engine was opened up for repairs, the valves and pistons were all covered in black carbon deposits. Keeping the RPM consistently below 2000 means the oil pump pressure is insufficient, leading to dry friction in critical components. One colleague's car had grooves worn into the piston rings, costing nearly 10,000 yuan for a major overhaul. Newer cars today are even more delicate, especially those with direct fuel injection—low RPMs make the injectors more prone to clogging. Plus, if the exhaust pipe doesn’t get hot enough, the catalytic converter can fail prematurely. Nowadays, I’d rather burn a bit more fuel to keep my daily RPM around 2000.

[LaHaven]

Driving at low RPM is like making someone squat halfway to work every day – problems are bound to arise over time. Firstly, carbon deposits will clog the spark plugs, making cold starts difficult. Secondly, prolonged low RPM operation slows down the water pump circulation in turbocharged cars, increasing the risk of overheating in older vehicles. My neighbor’s decade-old car ruined its cylinder head gasket this way. Additionally, engine oil provides poor lubrication at low temperatures and low RPM, accelerating wear on the crankshaft and bearings. The most frustrating part is the lack of power – even flooring the throttle feels sluggish when climbing hills or overtaking. Remember to find a safe stretch of road weekly and let the engine run at 3000 RPM for a few minutes.

[SanValerie]

People always say low RPM saves fuel, but in reality, long-term driving at low RPM actually increases fuel consumption. Last week, I used a friend's fuel consumption tester and found that the engine consumes 12% more fuel at 1500 RPM compared to 2500 RPM because the ECU has to compensate aggressively to maintain power. Prolonged low RPM operation also causes the ignition coils to wear out prematurely, and replacing a set costs around 700-800 RMB. Automatic transmissions suffer the most, as the gearbox often lingers in lower gears, causing the clutch plates to wear out extremely quickly. Not to mention the sensors—when the oxygen sensor gets clogged with carbon deposits, it starts sending erratic data. Nowadays, I teach my daughter to watch the tachometer while driving and avoid the 1500-1800 RPM range, which is the most prone to carbon buildup.