What are the effects of overfilling engine oil in a car?
3 Answers
The effects of overfilling engine oil in a car are as follows: 1. Overfilling engine oil can lead to reduced power output and increased fuel consumption: The crankshaft in a car engine requires lubrication to function properly. However, if the oil is overfilled to the point where the crankshaft is submerged in oil, it creates excessive resistance during rotation, resulting in lower power output and higher fuel consumption. 2. Increased carbon deposits: If too much oil is added, it can easily mix with the fuel injection and enter the combustion chamber, where the oil burns. This reduces the combustion efficiency of the gasoline, leading to carbon buildup in the vehicle. Excessive carbon deposits can cause reduced engine power, increased fuel consumption, and other issues that negatively affect the car's performance. 3. Accelerated aging of internal components: When engine oil is overfilled, the pressure between various internal parts of the car increases significantly. Prolonged use under such high pressure can accelerate the aging of these components. In particular, excessive pressure and severe aging of the crankshaft oil seal can lead to oil leaks in the car.
Last time I changed the engine oil during DIY car maintenance, my hands shook and I overfilled it by half a liter. After driving for a few days, I noticed the car wasn't performing well - sluggish acceleration and abnormally high fuel consumption. Later, I observed blue smoke coming from the exhaust pipe. My mechanic friend explained that excess oil increases crankcase pressure, which can rupture oil seals and cause leaks. More seriously, the high-speed rotating crankshaft whips the oil like an egg beater, creating foam that reduces lubrication effectiveness and accelerates engine wear. The most alarming issue is that surplus oil gets sucked into the combustion chamber where it burns, producing blue smoke and poisoning the catalytic converter. Eventually, I had to buy an oil extraction tube to remove the excess through the dipstick tube before the car returned to normal operation.
Having driven for fifteen years, I've seen many cases of overfilled engine oil. At its mildest, this issue increases fuel consumption and reduces power; at its worst, it can damage the engine. When the oil is overfilled, the crankshaft rotates like paddling in water, increasing resistance and naturally consuming more fuel. Foamy oil cannot form a proper oil film, leaving the camshaft and piston rings inadequately lubricated. I've personally witnessed a car develop an oil pan gasket leak due to excessive oil, requiring major engine disassembly for repair. It also leads to severe carbon buildup in the combustion chamber and clogging of the catalytic converter. Therefore, after an oil change, let the car sit for ten minutes before checking the dipstick level. The ideal level is slightly above the midpoint between the dipstick's upper and lower marks.
