What is the difference between cold start and hot start?

[DeAdriel]

The following are the differences between cold start and hot start of a vehicle: 1. Safety: Cold start is more harmful to the car, as more than 80% of engine wear occurs during the cold start phase. Hot start is the opposite. 2. Starting: Cold start is more difficult and takes longer to start the vehicle compared to hot start. This is because during cold start, the internal temperature of the engine is too low, making it harder for the air-fuel mixture to vaporize and combust. Additionally, during cold start, the engine oil temperature is insufficient. Even with the appropriate viscosity of oil, the viscosity is effectively too high at the moment of cold start, requiring time to raise the oil temperature to accelerate lubrication of engine components.

[DeEmily]

As a seasoned driver with years of experience, I often deal with cold starts in the morning—that is, starting the engine after it's been sitting overnight and completely cooled down. This is especially noticeable in winter, with significant vibrations and loud noises, taking several seconds to stabilize. It also consumes more fuel because the engine requires extra fuel injection to warm up, and poor lubrication leads to increased wear on parts. On the other hand, a hot start—like when you restart the engine shortly after stopping to run an errand—is quick, smooth, quiet, and fuel-efficient, making it ideal for frequent city driving. The challenge with cold starts lies in the weakened battery performance in low temperatures, so it's crucial to ensure battery health, regularly check engine oil, and avoid letting the engine sit cold for too long. Using hot starts for short stops can save money, improve maintenance, and make driving worry-free.

[VanAdeline]

I usually focus on fuel efficiency and environmental protection. Cold starts of the engine, when it's not warmed up, result in higher pollution and emissions, such as carbon dioxide and particulate matter, which harm the environment. Hot starts are more efficient and produce less pollution. In city driving, the start-stop system utilizes hot starts to reduce idling in traffic, saving fuel and keeping emissions cleaner. A quickly warmed-up engine is better for air quality. Temperature has a significant impact, with cold weather starts being worse. Using more hot starts can reduce your carbon footprint. During maintenance, replacing filters and using high-quality engine oil helps the engine reach operating temperature faster, making daily commutes greener.

[OBriella]

I know a bit about car repair. During cold starts, the engine oil is thick and viscous, leading to poor lubrication and increased metal friction, which accelerates wear and shortens the lifespan of parts, especially in cold regions. In contrast, during warm starts, the oil is already flowing, providing better lubrication, reducing wear, and allowing for quicker ignition. It's important to maintain the engine oil by changing it regularly to ensure proper fluidity and normal pump operation. Avoid frequent short stops and starts, as cold starts can harm the engine, while warm starts help extend engine health. Good driving habits can reduce repairs and save money.