What happens if engine oil is changed late?
4 Answers
Delayed oil change can lead to: 1. Deposited impurities corroding internal engine components; 2. Increased sludge formation, making it difficult for the oil pump to maintain pressure and potentially causing engine failure; 3. Oil degradation and ineffectiveness, reducing its lubrication and protection capabilities and accelerating component wear; 4. Oil thinning, losing its sealing properties and leading to gas leakage; 5. Reduced cooling performance. Engine oil, also known as motor lubricant, serves multiple functions including lubrication and friction reduction, auxiliary cooling, sealing against leaks, rust and corrosion prevention, and shock absorption. It consists of base oil and additives, with the base oil being the primary component that determines the fundamental properties of the lubricant.
I used to be a careless person, always forgetting things. Delaying oil changes is really bad. That time I postponed it for two months, and the engine started making clanking noises with a significant drop in power. When I took it for inspection, the oil had turned into black sludge, full of metal shavings and dirt, losing all its lubricating effect. The bearings and pistons were severely worn, and the repair cost nearly two thousand yuan. The mechanic said engine oil is like protective fluid—once expired, it thins and becomes acidic, corroding internal engine parts. Over time, the entire engine could seize. Now I don’t dare slack off—I check the odometer every month and change the oil promptly at 5,000 km, replacing the oil filter too, as a clogged one would be even worse. Daily driving also suffers—more noise and a fuel consumption increase of about 0.5 liters, making early oil changes more cost-effective in the long run. In short, delaying oil changes invites trouble—minor repairs at best, or a full engine replacement at worst. The risk is just too high.
I feel engine oil maintenance shouldn't be taken lightly. When I delayed an oil change during a busy work period recently, just three weeks overdue, I immediately noticed issues. The engine hesitated during startup, acceleration became sluggish, and the car felt underpowered. At the repair shop, they explained that aged oil loses viscosity, failing to properly lubricate components - this increases metal-on-metal friction and accelerates part wear. The repair for just one small component cost over 500 yuan. The bigger concern is that degraded oil produces acids that corrode engine passages while accumulated contaminants can clog oil channels. Long-term neglect could reduce engine lifespan by more than half - a full engine replacement costs tens of thousands. My friend had it worse - his prolonged delay led to engine failure on the highway, a genuinely dangerous situation. Now I check the dipstick weekly and strictly follow oil/filter change intervals to maintain optimal condition. Spending moderately on preventive maintenance outweighs the risks and costs of major repairs - absolutely worth it.
In my opinion, engine oil is the lifeblood of a car, and delaying its replacement is equivalent to slow suicide. Once the replacement interval is exceeded, the oil degrades and loses viscosity, leading to a sharp decline in lubrication capability. This directly results in increased friction inside the engine, such as between the crankshaft and bearings, causing rapid wear. The accumulation of contaminants also makes it easier to clog oil passages, affecting heat dissipation and leading to overheating. The outcome is invariably soaring repair costs, ranging from minor fixes costing a few hundred to major overhauls costing several thousand. Among the car owners I know, those who procrastinate on oil changes experience higher engine failure rates and an increase in fuel consumption by 0.3-0.8 liters per 100 kilometers. I recommend strictly following the manual's mileage intervals for oil changes, such as every 5,000 or 10,000 kilometers, and regularly checking the oil condition to nip problems in the bud. A healthy engine ensures smoother and safer driving.
