Can You Add Engine Oil When the Car is Hot?

[StevenLynn]

You can add engine oil when the car is hot. Below are the specific functions of engine oil: 1. Shock absorption and cushioning: When the pressure in the engine cylinder rises sharply, it suddenly increases the load on the piston, piston pin, connecting rod, and crankshaft bearings. This load is transmitted and lubricated through the bearings, providing a cushioning effect against impact loads. 2. Rust and corrosion prevention: The lubricating oil adheres to the surface of parts, preventing contact with water, air, acidic substances, and harmful gases. 3. Lubrication and friction reduction: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing bush. To prevent excessive wear, an oil film of sufficient thickness must be established between the sliding surfaces to separate them and reduce wear. 4. Cooling: Engine oil carries heat back to the oil tank and dissipates it into the air, helping the radiator cool the engine.

[MaverickLynn]

Adding engine oil to your car while it's running is theoretically possible, but I don't recommend doing so. After the engine runs, its temperature can reach several dozen degrees, causing the oil to expand. This makes the oil level appear lower on the dipstick than it actually is, which can easily lead to overfilling. Overfilling the engine oil increases the engine's burden, raises fuel consumption, and may even damage seals. There's also the risk of splashing hot oil, which can burn your hands or dirty components. I've seen a friend burn his fingers while hastily adding oil—it was quite painful. It's best to turn off the engine and wait 10 to 15 minutes for the temperature to drop before adding oil slowly, as this allows for a more accurate measurement of the oil level. For routine maintenance, make it a habit to check the oil when the engine is cold and use the correct viscosity grade to avoid unnecessary trouble. In emergencies, such as running low on oil during a long trip, carefully add a small amount, but don't make it a regular practice.

[DiGemma]

My old car has run 200,000 kilometers, and I occasionally add some engine oil when it's warm. However, I think there are significant risks. When the engine is hot, the oil expands, making the level appear low. If you add oil at this time, it's easy to exceed the limit. Too much oil can clog the crankcase ventilation holes, causing blue smoke in the car. Experience tells me that adding oil when the engine is cold is the safest and most accurate. After turning off the engine, wait for it to cool down a bit, then use the dipstick to check that the oil level is between the min and max marks. If the car is frozen in cold weather, you can wait until it warms up slightly before handling it. The key is not whether you can add oil, but whether you add it accurately. Regularly check the condition of the engine oil to avoid carbon buildup and wear, extending the car's lifespan. Maintaining a car is like taking care of a partner—take it step by step and don't rush.

[VanAlan]

It's common to add oil to a hot engine in the workshop, but it's risky. The engine is scorching hot, and adding too much oil when it's expanded by heat can damage piston rings and seals, potentially wasting money on repairs. The proper way is to wait a few minutes after the engine stops until the temperature drops slightly, then add the right amount of oil—don't pour the whole bottle. Maintaining the correct oil level is crucial: too little accelerates wear, and too much causes leaks. Safety first is always right—wear gloves and take your time, no rush. Adding oil to a cold engine is more accurate and worry-free.

[AugustDella]

When I was learning to drive, I once added engine oil while the car was warm, which resulted in excessive oil consumption. Later, I realized that thermal expansion of the oil misled the level reading, and the correct level should be between the min and max marks when checked on a cold engine. After turning off the engine, wait a bit for it to cool down, then gently measure with the dipstick and add the appropriate amount to avoid mistakes and burns. Beginners should consult experts or refer to the manual for guidelines, as maintaining regular upkeep habits can make driving smoother.