What happens if motor oil is not changed for a long time?
4 Answers
The consequences of not changing the oil for a long time are as follows: 1. If the oil is not changed for a long time, as the oil's lifespan deteriorates, its lubrication ability will rapidly decline, preventing the engine from receiving proper lubrication and leading to abnormal wear. 2. Metal debris cleaned by the oil cannot be expelled and accumulates inside the engine, causing dirt and generating a large amount of sludge. 3. The engine may experience increased fuel consumption, reduced power, difficulty starting, abnormal shaking, and poor operation. In severe cases, the engine may be directly rendered unusable. Here are the functions of motor oil: 1. Lubrication: There are many moving friction surfaces inside the engine. The oil forms a film between these surfaces to achieve lubrication and anti-wear effects. 2. Cleaning: The movement of engine components causes wear and produces metal debris. The oil continuously circulates inside the engine through the action of the oil pump and carries these metal debris back to the oil pan. 3. Cooling: The continuous circulation of oil inside the engine can carry away the heat generated by the engine and cool it through the oil cooler. 4. Sealing: The oil film formed on the surface of the engine cylinder walls and the inner surface of the valve guides can provide a sealing effect to prevent leaks.
I used to think changing engine oil didn't matter, until one time I drove my car for nearly 30,000 kilometers without an oil change, and the engine ended up with cylinder scoring! The mechanic explained that degraded oil loses viscosity, causing metal components to grind against each other like dry friction, eventually wearing out piston rings. Plus, accumulated metal particles in the oil act like abrasive paste. The scariest part was sludge clogging oil passages, leading to temperature spikes in unlubricated areas and even cylinder wall scratches. The engine repair cost me over 5,000 yuan. Now I change oil religiously—going over 3,000 km makes me nervous.
Engine oil is just like blood - if you don't change it when it expires, all kinds of problems will arise. First, the engine noise becomes louder with a buzzing sound when driving; then fuel consumption surges dramatically - my colleague's SUV went from 8L/100km to 11L/100km; finally, even the power becomes sluggish, with RPM failing to climb even when flooring the accelerator during overtaking. Not to mention sludge clogging the filter, preventing new oil from circulating. A friend's car directly showed a red warning light and broke down, with towing fees costing ten times more than an oil change. Actually, even full synthetic oil needs changing after at most 10,000 kilometers - don't try to save on such small expenses.
The most dangerous aspect of expired engine oil is the formation of acidic substances that gradually corrode metal components. Seals will harden and crack, causing oil leaks and leaving the underside of the chassis constantly wet. Cooling efficiency deteriorates, triggering overheating warnings during high-speed summer driving. Worn bearings can even make the steering wheel vibrate. I once noticed blue smoke from the exhaust pipe—a sign of oil entering the combustion chamber, which even damaged the catalytic converter. With regular oil changes, an engine can easily last 300,000 kilometers. This is definitely not an area to cut corners.
