How long should you wait to turn off the engine after driving on the highway?
3 Answers
After high-speed driving, do not suddenly stop and turn off the engine. You should wait for more than a minute after the turbocharging system stops working before shutting it down. However, in general, it takes several minutes from leaving the highway to parking, so there is no need to extend the low-speed driving time additionally. More details are as follows: 1. Some cars can be turned off immediately after high-speed driving: Some car engines have a cooling system that can continue to operate for a while after the engine is turned off to help dissipate heat from the turbocharger. For such cars, there is no need to idle after high-speed driving; you can turn off the engine directly. 2. Cooling principle: When the engine is just started, the coolant will undergo a small cycle. At this time, the coolant does not pass through the radiator for cooling, which helps the engine warm up quickly. When the engine reaches its normal operating temperature, the coolant will switch to a large cycle, passing through the radiator to dissipate heat, thereby maintaining the engine within a reasonable temperature range.
It's good to wait a minute before turning off the engine after highway driving, as the engine gets particularly hot at high speeds, especially in turbocharged models where the turbocharger reaches extremely high temperatures during operation. I've noticed that if you don't let the car idle for a while to cool down, the turbo bearings could warp or get damaged once the lubricant stops flowing, and repairs can be really expensive. However, this isn't necessary for all cars—naturally aspirated engines aren't as affected. Generally, it's recommended to idle for 1 to 2 minutes to let the fan and cooling system do their job before turning off the ignition. When I drive a turbocharged car, I usually check the dashboard to make sure the temperature drops to normal before shutting it off—it's a more worry-free way to maintain the car.
After high-speed driving, it's best not to turn off the engine immediately, especially when the engine is at high temperatures during long-distance trips. I believe waiting about 90 seconds is safer to avoid overheating of turbo components and shortening their lifespan. This isn't an overreaction but a precaution against common issues: for example, lubricant solidifying on hot parts, which may cause malfunctions during the next startup. I've seen a friend who didn't pay attention to this and ended up spending thousands on repairs later. Maintaining this habit in daily driving is simple and can also extend engine durability. Waiting a moment after parking is crucial for long-term vehicle use.
