What happens if too much engine oil is added to a car?

[IvanLynn]

Adding too much engine oil to a car can lead to increased fuel consumption. During operation, the crankshaft and connecting rod big end will undergo intense agitation, increasing internal power loss in the engine. Additionally, more oil will splash onto the cylinder walls, potentially causing oil burning and exhaust issues. Therefore, the oil level should be maintained between the upper and lower marks on the dipstick. Below is some relevant information about engine oil: 1. Engine oil significantly impacts the performance and lifespan of the engine, so it is crucial to strictly follow the vehicle's manual to select oil of the same series, service grade, and viscosity grade. The oil recommended in the manual is determined based on the engine's performance and the ambient temperatures in the sales region, providing essential guidance for oil selection and leaving a considerable safety margin. It is also one of the prerequisites for warranty claims during the engine's warranty period. 2. Select the viscosity grade based on the engine's technical characteristics. For new engines, choose oil with lower viscosity to ensure proper break-in during the initial use period. For older or more worn engines, opt for higher viscosity oil to maintain the required oil pressure and ensure adequate lubrication.

[Antonio]

I accidentally overfilled the engine oil when changing it myself, and after driving, I noticed the engine noise became louder with a buzzing sound during acceleration. A mechanic at the repair shop explained that too much oil causes the crankshaft to violently churn, creating foam. When air bubbles enter the lubrication system, proper lubrication is compromised, leading to increased wear and even cylinder damage. Rising oil pressure can also force oil seals to leak—I found oil stains on the ground after parking. I immediately went to the shop to drain the excess oil, as prolonged overfilling could burst the oil filter or damage components, resulting in costly repairs. Since then, I always carefully check the dipstick when changing oil to ensure it doesn’t exceed the upper limit, avoiding regrets. During maintenance, I’d rather slightly underfill and top it up to the middle mark after the engine cools down—safe and worry-free.

[ThomasDella]

Having been a car enthusiast for years, I know that overfilling engine oil is no trivial matter. It increases crankshaft resistance, reduces lubrication effectiveness due to foaming, and accelerates internal engine wear. Excessive oil pressure may cause leaks, such as front axle seal failure leading to oil dripping on the floor. Once when helping a friend, his engine suddenly vibrated violently after highway driving with overfilled oil - we checked the dipstick to find it exceeded limits, and had to extract half a liter with a suction tube to stabilize it. Remember: always measure the manufacturer-recommended quantity before oil changes, never estimate. Overfilling also increases fuel consumption - a lose-lose situation. Make regular maintenance a habit to avoid such small mistakes damaging your precious engine.

[OAllison]

Excessive engine oil directly threatens driving safety. The surplus oil can foam, leading to insufficient lubrication and severe internal engine friction, which may cause unexpected malfunctions at high speeds and increase the risk of accidents. Long-term neglect can also worsen fuel consumption and pollution. I recommend checking the dipstick level after each refueling once the car is stationary. If the level exceeds the limit, promptly drain the excess to maintain normal operating conditions. Never be careless about it.