Should an automatic transmission car be in P or N gear when warming up?
3 Answers
An automatic transmission car should be in P gear when warming up, because the P gear provides sufficient safety by locking all four wheels to prevent rolling, and the engine speed in P gear is relatively higher, allowing the car to warm up faster. The ultimate goal of warming up is to quickly activate various fluids inside the car in a short time. To achieve this, we can choose to idle the vehicle in place. When idling, the engine does not rotate too fast, allowing the fluids to be gradually activated by the engine. Since the piston movement is not particularly rapid, it won't cause significant damage to the engine. However, if the vehicle is started without waiting for the oil to fully lubricate the engine, the cylinder walls inside the engine may be directly damaged by piston movement, a phenomenon commonly known as cylinder scoring.
When it comes to which gear to use when warming up an automatic transmission car, I believe the P (Park) gear is the most reliable choice. Why do I say that? From a safety perspective, the engine is running during the warm-up process, and engaging the P gear completely locks the transmission, preventing the vehicle from accidentally moving, especially when parked on a slope or uneven road. I once had a friend who was a beginner and used the N (Neutral) gear to warm up the car but forgot to engage the handbrake, causing the car to roll slightly and almost hit a wall. If this had happened in a crowded place, it could have been dangerous. Warming up the car is meant to let the engine gradually warm up, usually taking just a minute or two, and using the P gear is worry-free and stable. Additionally, some car models’ automatic transmissions are designed so that using the P gear reduces unnecessary friction, making it harmless to the car in the long run. Of course, some people think the N gear is also fine, but that requires extra checks on the handbrake, which is much more troublesome. In short, safety comes first, and choosing the P gear is the simplest and most reliable option.
When it comes to warming up the car, I have my own routine—just put it in P gear and that's it. From a vehicle maintenance perspective, an automatic transmission is actually more stable in P gear, reducing the risk of internal wear. If you warm up the car in N gear, the transmission stays in neutral, which might cause minor friction between the engine and the drivetrain. Over time, this could lead to increased wear, especially in older cars. I remember once driving a friend's old car—he always warmed it up in N gear, and later the transmission started making strange noises. The mechanic said it was due to this very habit. Warming up the car doesn’t take long—just 30 seconds to a minute is enough until the engine temperature rises before driving off. The key is to focus on the coolant temperature gauge or oil pressure, avoiding unnecessary fuel waste by overdoing it. If you're driving in the city, warming up in P gear is a one-step solution, avoiding unnecessary gear shifts that could compromise safety. Overall, developing good habits pays off in the long run for your car's longevity.
