What are the effects of not changing engine oil for a long time?

[StMarley]

Long-term failure to change engine oil will result in: increased engine noise, poor internal lubrication leading to accelerated wear of internal components, and reduced engine lifespan. For semi-synthetic oil, replacement is required every 6 months or 5,000 kilometers. If full synthetic oil is used, it should be replaced within 10,000 kilometers or one year. The cooling effect of oil diminishes as deteriorated oil significantly reduces heat dissipation capability since oil's heat absorption and thermal conductivity are far superior to water. The lubrication function declines as the viscosity of oil gives it strong adhesion, allowing it to form a protective film between gears, shafts, and other components for smooth operation and reduced wear. Deteriorated oil largely loses this capability.

[AustinDella]

As an ordinary car owner, I personally experienced the troubles caused by delaying an oil change. During that busy period at work, I neglected maintenance and went nearly a year without changing the oil. Later, while driving, I noticed the engine noise was unusually loud, acceleration was sluggish, and fuel consumption had significantly increased. When I took it to the repair shop for inspection, the oil was as black as ink, filled with impurities and sludge. The mechanic explained that aged oil greatly reduces lubrication effectiveness, increasing internal component friction and accelerating wear. In severe cases, it can also lead to carbon buildup, clogging oil passages, and even causing overheating damage. That repair cost me a lot of money, and now I understand that changing the oil on time is the best way to protect the engine. Don’t risk big problems to save a little money—set a reminder for regular maintenance.

[Mallory]

I have some friends who always try to save money by skipping oil changes, only to end up paying more in the long run. Over time, engine oil oxidizes and deteriorates, becoming as thick as glue and losing its lubricating properties. This increases friction between engine components, shortening their lifespan and potentially causing overheating and seizing. Additionally, old oil can't effectively clean the engine internals, leading to more carbon deposits and metal shavings buildup. I once saw a car that hadn't had an oil change for two years, requiring a major engine overhaul costing thousands. It's recommended to change the oil every 5,000 to 10,000 kilometers or about every six months, using quality brand oil products. Simple regular checks and maintenance can prevent these risks, saving both hassle and effort.

[AthenaRose]

As a new car owner, I forgot to change the oil last time, and the car sounded unusually loud. After asking a friend, I learned that aged oil loses its lubricity, increasing fuel consumption and reducing power. I rushed to get it changed, and the smoothness returned. An experienced driver told me that regular oil changes are crucial, otherwise, it can wear out the engine internals, leading to expensive repairs.