No oil change for one and a half years, mileage not reached, any impact?

[Carole]

Even the best engine oil will deteriorate after one year of use. Full synthetic oil should be changed even if the mileage limit hasn't been reached. The impacts are as follows: Possible insufficient oil volume: The engine continuously consumes oil during operation, though at a relatively slow rate. As long as there's no oil burning, oil shortage typically won't occur within the normal oil change interval. However, in certain situations like vehicle deceleration, bumpy road conditions, or body tilting, the oil pump may not be able to draw oil properly. Accelerated oil aging: Engine oil not only provides lubrication but also cooling. Although the heat absorbed by the oil is ultimately dissipated through the engine and coolant, insufficient oil volume reduces circulation cooling efficiency, potentially leading to higher oil temperatures and faster oil degradation. Increased engine sludge: Prolonged oil change intervals cause oil volume to decrease while the engine continues running, continuously generating particles. These particles keep dissolving in the oil until it becomes increasingly viscous. Potential oil filter failure: The oil filter is designed to clean the oil. After leaving the oil pump, all oil passes through the filter before reaching lubrication points. After lubrication, the oil returns to the oil pan and gets recirculated by the pump, passing through the filter again each time.

[AdelynFitz]

I've been driving for almost ten years and have seen this issue countless times. The shelf life of engine oil is much shorter than you might think. Even if you haven't driven the recommended mileage, exceeding a year and a half is pushing it. Engine oil absorbs moisture, oxidizes, and breaks down, reducing its lubricating properties by half. The most obvious sign is metallic friction noises during cold starts. My neighbor waited two years without changing it and ended up spending over 8,000 yuan on engine repairs. My advice: check the dipstick. If the oil is black like soy sauce and feels gritty between your fingers, change it immediately! Don't just rely on the odometer—the maintenance manual specifies a dual standard of 'six months or 10,000 kilometers.' Pay special attention to oil emulsification issues in vehicles used for short trips.

[JoannaLee]

Maintaining a car is like taking care of a pet; you need to feed it good 'food' regularly. The harm of overdue engine oil doesn't show up immediately, but long-term accumulation can be fatal. Sludge clogging the oil passages is like a blood clot in your veins, leading to piston ring sticking and a surge in fuel consumption. During my last maintenance, I saw a car with its filter full of sludge resembling chocolate sauce. Don't hesitate to spend a few hundred on maintenance fees. Remember, the effectiveness of oil additives lasts only 6-12 months, after which the anti-wear components become ineffective. Another benefit of regular oil changes: the mechanic can also check for oil leaks under the chassis, identifying potential issues early.

[BenjaminDella]

Engine oil is a living fluid. Once opened, it continuously oxidizes and deteriorates, a chemical process not limited by mileage. Even when parked in a garage, temperature fluctuations cause the oil to absorb moisture and form emulsions. Degraded oil in the engine is like expired cooking oil—not only does it lose its lubricating properties, but its acidic components also corrode bearings. During your next maintenance, ask the technician to conduct an oil sample test; you'll find excessive iron particles and acid levels. Additionally, note that oil deteriorates faster in humid southern regions, and vehicles parked in basements require stricter adherence to replacement schedules.

[Amelia]

Here's a real-life case: My friend's car only drove 3,000 kilometers in two years, and it ended up with cylinder scoring requiring a major overhaul. Modern engines have extremely high precision, with oil film thickness ten times finer than a human hair. Deteriorated engine oil causes the oil film to rupture, resulting in direct metal-to-metal contact between the camshaft and crankshaft. Here's a self-check method: When the engine is cold, pull out the dipstick and smell it. Normally, it should have a faint fuel odor. If you detect a sour or burnt smell, change the oil immediately. Don't forget to replace the oil filter simultaneously, as old filters contain a lot of metal debris. Remember this maintenance rule: Change mineral oil every six months, and even full synthetic oil shouldn't exceed one year.

[StGenevieve]

This question actually has deeper implications. Engine oil is not just a lubricant, but also acts as a cleaner and coolant for the engine. Overused oil can deposit sludge, reducing cooling efficiency and leading to engine knocking. Especially for turbocharged models, the turbo bearing temperature can reach as high as a thousand degrees, relying entirely on oil for cooling. Actual tests have shown that oil not changed for two years can lose up to 40% of its viscosity under high temperatures, triggering the oil pressure warning light during acceleration. It's advisable to get into the habit of checking the maintenance manual—manufacturers' recommended oil change intervals include a safety margin. Don't be misled by marketing jargon; so-called long-life oils have a maximum shelf life of about two years.