Can Automatic Transmission Cars Coast in Neutral?

[SanElla]

Automatic transmission cars should not coast in neutral as it can be harmful to the automatic transmission. Here are the reasons why coasting in neutral is not advisable: 1. The automatic transmission requires lubrication, and when the gear is shifted to N while driving, the oil pump cannot supply oil properly for lubrication, causing the internal components of the transmission to overheat and potentially leading to damage. 2. Coasting in neutral is extremely harmful to the automatic transmission. Below is additional information: 1. As the name suggests, an automatic transmission does not require the driver to manually shift gears; the vehicle automatically selects the appropriate gear based on driving speed and traffic conditions. 2. Automatic transmissions still have corresponding gears. Whether manual or automatic, more gears generally lead to better fuel efficiency. 3. For short stops, such as at a brief traffic light, simply pressing the brake is sufficient. 4. If the stop lasts longer than 2 minutes, it is advisable to shift to N gear to protect the transmission and prevent the transmission oil from overheating.

[LaGenesis]

Having driven automatic transmissions for over a decade, I sincerely advise against coasting in neutral. Automatic and manual transmissions have completely different structures. When in neutral, the oil pump speed can't keep up, leading to poorer lubrication and cooling - those precision planetary gears and solenoid valves all operate submerged in oil. I've personally witnessed cases where coasting just 10+ km on highways in N gear caused clutch plates to burn out as transmission temperatures skyrocket. Manufacturer manuals explicitly prohibit neutral coasting, and this isn't just scare tactics. If you really want to save fuel, it's more practical to anticipate road conditions early and control speed with throttle input.

[EloiseDella]

Last time I tried coasting in neutral, the transmission immediately threw a fault code. When an automatic transmission is in N gear while coasting, the driveshaft rotates but the oil pump speed is low, which can cause dry friction in components like the sun gear. Especially on long downhill sections, the transmission oil temperature rises quickly and can easily trigger overheating protection. The mechanic said I was lucky not to burn out the solenoid valve, as replacing the valve body would cost several thousand. Now I always use D gear with brake assistance to control speed, which is much safer.

[MacCole]

From a mechanical principle perspective, automatic transmissions require oil pressure to maintain operation. When in Neutral gear, the excessive speed difference between the driving and driven discs causes abnormal wear on the torque converter's lock-up clutch. I once monitored with an OBD scanner and found oil pressure during coasting in Neutral was 40% lower than normal, which is particularly damaging to the hydraulic valve body. Moreover, modern vehicles have intelligent protection systems that automatically shift back to Drive gear if Neutral is engaged at excessive speeds.

[McJace]

My neighbor Old Zhang ruined his transmission by coasting in neutral. He said he wanted to save fuel, but ended up spending over 8,000 yuan on repairs. In automatic transmissions, the oil pump pressure is insufficient at engine idle speed, and those capillary-like oil passages simply can't supply enough lubrication. Especially in older models with torque converters, the transmission starts shaking after coasting more than 3 kilometers. Actually, test data shows that coasting in gear with ECU fuel cutoff is more fuel-efficient than coasting in neutral.

[LaRichard]

I used to hear experienced drivers say that coasting in neutral saves fuel, but I regretted trying it myself. Now I know that automatic transmissions rely on transmission fluid for cooling, and the cooling efficiency drops by 70% when coasting in N gear. Even scarier is the moment you shift back to D gear—the impact force on the driveline with that loud clunk is equivalent to three normal gear shifts. When my 6AT was opened up by the mechanic, the thrust washers were found shattered. If you must use N gear for temporary towing, keep the speed below 40 km/h and limit the distance to within 2 kilometers.