Should You Shift to Neutral at a Red Light in an Automatic Transmission Car?
2 Answers
Whether to shift to neutral at a red light in an automatic transmission car depends on whether the power transmission device may overheat and fail. Details are as follows: 1. Theoretically, for automatic transmissions with a radiator, if the red light wait time does not exceed 30 seconds: shifting to neutral is unnecessary. 2. If exceeding 30 seconds: it is recommended to shift to neutral. 3. For automatic transmissions without a radiator: shifting to neutral is advised. 4. For vehicles equipped with auto start-stop: simply keeping the brake pedal pressed is sufficient. Relevant information about automatic transmissions is as follows: 1. Classification: There are various types of automatic transmissions, including AT, CVT, DCT, and DSG. 2. AT and CVT: AT and CVT transmissions are grouped together as they both use a torque converter as the power transmission device, relying on circulating hydraulic fluid to transfer power. The heat generated by the torque converter is dissipated by the hydraulic fluid to the transmission radiator, preventing the fluid from losing performance due to overheating. These devices are equipped with radiators. 3. DCT and DSG: DCT and DSG are called dual-clutch automatic transmissions, with the power transmission device further divided into wet and dry dual clutches. Wet dual clutches also have radiators, while dry dual clutches lack radiators, with heat dissipation efficiency equivalent to a manual transmission clutch. Overheating can burn the clutch plates.
I've been driving automatic transmission cars for over thirty years, and the issue of shifting to neutral at red lights is quite common. To be honest, most of the time I just keep my foot on the brake and stay in D gear—it's easier and safer. Frequently switching gears from D to N and back causes extra wear on the transmission's internal gears, which can shorten its lifespan over time. Some say shifting to neutral saves a bit of fuel, but modern engines are so efficient that the fuel consumption difference when idling in D gear is negligible—real-world tests show less than a 1% difference at red lights. It's better to focus on driving habits than waste time on such minor details. For long red lights, like at railroad crossings, I do shift to neutral to give my foot a break. Cars with auto start-stop systems are even simpler—the engine shuts off when stationary, so there's nothing to worry about. The key is not to develop bad habits. Cars are meant to serve us, so convenience should come first.
