Is it serious if the engine oil hasn't been changed for over a year?

[VanDawson]

Not changing the engine oil for over a year is indeed serious and can have certain impacts on the engine. Engine oil that has been used for an extended period will see its performance degrade or even become ineffective, failing to protect the engine and instead increasing the wear and tear on components. If the oil deteriorates severely, its cooling and heat dissipation capabilities will significantly decrease, leading to overheating inside the engine, which can further cause issues such as bearing seizure and cylinder scuffing. Therefore, regardless of how long the oil has been in use, it needs to be replaced once it deteriorates. The longer the oil goes unchanged, the higher the likelihood of it deteriorating. Car owners should strictly adhere to the oil change intervals to prevent severe damage to the engine caused by deteriorated oil. Generally, the replacement interval for full synthetic oil is one year or within 10,000 kilometers; for semi-synthetic oil, it's within 7,500 kilometers or 6-8 months; and for mineral oil, it's within six months or 5,000 kilometers. These intervals are just reference values, and the actual time for changing the oil should be determined based on specific conditions.

[MacMaverick]

I think not changing the engine oil for over a year is really serious. I remember with my old car, I was too busy and delayed the oil change for more than a year. As a result, the engine noise increased, and I always felt a lack of power when starting. When I took it to the repair shop, the mechanic said the oil had become as thick as syrup, with poor lubrication, causing accelerated wear on the piston rings and camshaft. Exceeding the interval for so long means the additives in the oil break down, sludge builds up and clogs the oil passages, and it can even corrode the seals, leading to oil leaks. If this continues, engine overheating or cylinder scuffing could occur, and repairs wouldn't be cheap—replacing an engine could cost tens of thousands. I advise everyone not to follow my example. Regularly check and change the oil every six months or 10,000 kilometers—it saves both hassle and money. If you've delayed too long, take it to a professional shop for a thorough inspection immediately, before small issues turn into big problems.

[DiLillian]

From my perspective, not changing the engine oil for over a year is no small matter. Engine oil doesn't just lubricate the engine; it also helps with cooling and cleaning internal impurities. Over a year, the oil oxidizes and deteriorates, becoming either too thick or too thin, which reduces its protective effectiveness. Especially with old oil, sludge can easily form, clogging the oil pump or filter screen, potentially leading to insufficient oil pressure—resulting in dry friction between engine components and accelerated wear. Prolonging this can cause a sharp increase in fuel consumption, and the exhaust might even start smoking. I recommend checking the dipstick immediately. If the oil appears black or cloudy, it's a clear sign it needs to be changed right away. It's best to follow the manual's recommendations and not exceed the suggested intervals—safety first.

[EstherDella]

I'm the type who values cost-efficiency, so I believe the consequences of not changing the engine oil for over a year can be quite troublesome. A new oil change costs a few hundred bucks, but repairing a worn-out engine could set you back thousands or even tens of thousands—using oil beyond its service life leads to degradation, which corrodes internal components like pistons or valve stems, causing irreversible wear. Over time, fuel consumption increases, making driving more expensive. I've delayed it before, and when I finally changed the oil, the mechanic said it was too dirty, requiring extra time and effort for cleanup and maintenance. My advice: don’t take the risk—get an oil change and inspection immediately to check for any unusual engine noises. Developing a habit of regular maintenance is far more cost-effective in the long run.

[Ivy]

As a safety-conscious car owner, I believe going over a year without an oil change is extremely risky. Insufficient engine lubrication can cause overheating from friction, potentially leading to sudden engine failure - not a minor issue on highways. Degraded oil reduces engine performance under heavy loads, making uphill climbs or overtaking maneuvers particularly hazardous. Aged oil may also cause internal corrosion, leading to oil leaks or smoke emissions, significantly increasing accident risks. I experienced this once myself - only addressing it when the check engine light came on. I strongly recommend prompt action: inspect your oil condition immediately and never delay maintenance to prevent catastrophic consequences.

[LaZachary]

When I first learned to drive, I forgot to change the oil for over a year. As a result, the engine made a creaking sound when I started the car, which scared me into a cold sweat. The mechanic said old oil has weak protective properties, causing metal parts to wear against each other, and over time, it could ruin the engine. He recommended changing the oil every 5,000-7,000 kilometers or every six months—if overdue, watch out for unusual noises or abnormal fuel consumption. Since then, I’ve stuck to regular maintenance, and the car runs much smoother—fresh oil extends engine life and is more eco-friendly too.