In daily driving, many car owners often find themselves puzzled — even though they drive in what they believe is a “normal way.” They avoid sudden acceleration, refrain from overloading, and try not to drive aggressively. Yet, during routine maintenance, the technician still points out noticeable signs of engine wear in the car motor. These signs are sometimes accompanied by slightly higher fuel consumption and reduced power output.
Why does this happen? Does “normal driving” still fail to prevent engine wear?
In reality, engine wear is not caused solely by harsh driving. Many subtle driving habits, overlooked maintenance details, and hidden system issues can quietly accelerate engine wear. Even when we believe we are using the car motor properly, these unnoticed factors may still increase internal friction, leading to gradual performance decline, rising fuel consumption, and even potential mechanical failure over time.
Today, let’s take a closer look at the most common — yet easily ignored — causes of engine wear. By understanding these factors, you’ll know how to better protect your car motor in everyday use, helping it stay in peak condition for longer.
1. Lubrication System Failure: The “Direct Killer” of Engine Wear
Over 90% of the moving parts inside a car motor—such as pistons, crankshafts, and camshafts—rely on an oil film formed by lubricating oil to prevent metal-to-metal contact. Once the lubrication system fails, metal components directly rub against each other, causing dry friction, which rapidly accelerates engine wear.
Lack or Deterioration of Lubricating Oil
- Insufficient oil level: Failing to regularly check the oil level, or oil loss caused by seal leakage or oil burning (piston ring sticking), leads to a shortage of lubrication oil that cannot fully cover all friction surfaces.
- Oil deterioration: Exceeding the recommended oil change interval (by time or mileage) causes the oil’s viscosity, oxidation resistance, and cleaning ability to degrade. When the oil becomes dark or forms sludge, it can no longer provide an effective oil film—and may even carry impurities that scratch metal surfaces.
Incorrect Oil Grade or Viscosity
- Using oil that is too thin: For example, using 0W-20 instead of the required 5W-30 can result in the oil film breaking under high temperature, failing to protect parts under heavy loads.
- Using oil that is too thick: For instance, using 10W-40 instead of 0W-20 causes poor flow in low temperatures, meaning oil cannot reach friction points quickly during startup. This leads to cold start wear, which accounts for over 70% of total engine wear.
Faults in the Lubrication System Components
- Oil pump failure: When the pump cannot generate sufficient oil pressure, lubricating oil fails to reach key components such as the crankshaft journals and camshaft lobes.
- Clogged oil filter: When the filter element becomes blocked by impurities, the bypass valve opens, allowing unfiltered oil (containing metal debris and dust) to circulate and scratch the friction surfaces.
- Blocked oil passages: Using low-quality oil or skipping oil changes for too long can lead to sludge buildup in the oil passages of the cylinder block and head, resulting in local oil starvation and wear—especially on camshaft lobes.
