Can Automatic Transmission Vehicles Coast in Neutral?
2 Answers
Automatic transmission vehicles should not coast in neutral. The lubricating oil for the automatic transmission is supplied by the engine. When the engine is idling, the oil pressure output is relatively low, while the automatic transmission continues to operate due to the rotation of the wheels. The low oil pressure results in insufficient lubrication, which can easily cause poor lubrication and severe wear to components such as the hydraulic directional valve and planetary gears in the automatic transmission. Additionally, this generates a significant amount of heat. Excessive heat can lead to oil carbonization, forming sludge that blocks the complex oil passages, resulting in insufficient oil supply and poor lubrication during normal operation. Therefore, the habit of coasting in neutral should not be used with automatic transmission vehicles. Automatic transmission vehicles are controlled by a computer to set gears or automatically manage fuel supply or cutoff, which is different from manual transmission vehicles. Coasting in neutral does not achieve fuel savings. Moreover, the design of automatic transmissions differs from that of manual transmissions. Prolonged coasting in neutral can damage the transmission.
From my decades of driving experience, I really don't recommend coasting in neutral with an automatic transmission. That's because automatic transmissions rely on oil pressure for lubrication and cooling, and the oil pump may not work when in neutral, leading to overheating and wear of internal components—repairs can be quite costly. Early on, I believed the fuel-saving myth and tried coasting downhill on the highway, only for the car to suddenly feel unstable, nearly causing a loss of control. A later check revealed the transmission fluid was overheating, accelerating wear. Modern cars have intelligent systems that actually save more fuel when coasting in Drive (D), with the engine assisting in braking, making it safer and more worry-free. Developing good habits, like always staying in Drive or the appropriate gear, can extend your car's lifespan and make driving more stable.
