Why is it necessary to change car engine oil?

[MadelynDella]

Reasons for changing car engine oil are as follows: 1. Engine oil generates impurities during lubrication: During the lubrication process, engine oil is gradually consumed, producing impurities that affect its lubricating performance, hence requiring regular replacement. 2. Prolonged failure to change oil leads to reduced cooling effectiveness: Cooling is one function of engine oil, and after extended use, its cooling capability diminishes. 3. Not changing oil results in decreased sealing performance: Due to prolonged use and heating, chemical reactions inevitably occur in the oil, reducing its sealing properties. 4. Engine oil gradually depletes during use: When the piston moves downward, a thin oil film forms on the cylinder wall. During high-speed operation, some oil is drawn into the combustion chamber and burned along with the air-fuel mixture.

[DiSamuel]

I've been driving for twenty years, and changing engine oil is as essential as eating. Engine oil is like the blood of the engine—without it, the metal parts inside would rub against each other and wear out, leading to cylinder scoring and eventual engine failure over time. Moreover, the engine generates high temperatures during operation, and the oil helps dissipate heat. If the oil ages and thickens, it loses its cooling effectiveness. The most noticeable difference is that after every oil change, the engine runs quieter and accelerates more smoothly. If you don’t change the oil on time, sludge can clog the oil passages, and repairs could cost thousands. I change the oil every six months or 5,000 kilometers, always replacing the oil filter at the same time—this way, my beloved car can keep running smoothly for years to come.

[DiChase]

As an owner with an engineering background, I've discovered that engine oil does far more than just lubricate. It also captures metal particles to prevent cylinder wall scratches, neutralizes acidic substances from combustion, and maintains internal engine cleanliness. As mileage accumulates, high temperatures cause oil oxidation and additive degradation. When viscosity drops or contaminants exceed limits, the oil loses its protective properties. I once detected excessive metal content in oil analysis, realizing the dangers of accelerated wear. Now I follow the manual's schedule for full synthetic oil changes - far more economical than engine repairs. I've also learned to check dipstick color; darkened oil signals replacement time.

[McJaxon]

Changing engine oil can really save you big money. My neighbor's car needed a major engine overhaul due to delayed oil changes, costing over 7,000 yuan. In contrast, I change my oil twice a year for just over 500 yuan, which works out to about 2 yuan per day for peace of mind. Long-term neglect of oil changes leads to carbon buildup, making the engine consume more fuel—the additional fuel costs can actually exceed maintenance expenses. Additionally, regular oil changes enhance used car resale value. My friend's vehicle with complete maintenance records sold for 6,000 yuan more than same-year models. Nowadays, I always ask the mechanic to inspect the brakes and cooling system during oil changes, completing basic safety checks in the process.