Should Fully Synthetic Engine Oil Be Replaced After One Year or 5,000 Kilometers?
2 Answers
Fully synthetic engine oil should be replaced after one year or 5,000 kilometers of use. Generally, the replacement interval for fully synthetic oil is one year or 10,000 kilometers. Since it has already been used for one year, the oil should be promptly replaced to prevent degradation of the old oil from affecting vehicle performance. Typically, engine oils should not be mixed, and it is advisable to use the original oil. If the brand or specification of the new oil differs from the original, it may damage the car's engine. When changing the oil, ensure the old oil is completely drained before adding the new oil. Pay attention to the oil quantity when refilling. Add the appropriate amount based on the vehicle's displacement—never overfill or underfill. Excessive oil can cause internal power loss during engine startup and may lead to oil burning issues. Conversely, insufficient oil can result in inadequate lubrication between engine bearings and journals, accelerating wear and potentially causing severe damage like bearing seizure.
I've been driving for many years and often encounter oil change issues. Last year, after using full synthetic oil in my car, I only drove 5,000 kilometers but didn't change it for a year. I started noticing increased engine noise and less smooth acceleration. Later, consulting an expert, I learned that oil exposed to air oxidizes and deteriorates, with additives losing effectiveness. Even with low mileage, it needs changing to avoid increased internal wear. Although full synthetic oil is durable, its shelf life is generally only about a year. For safety and reliability, I now insist on regularly checking the oil's color and viscosity, changing it once it turns dark or thick. This habit has helped me avoid major repair costs and keeps the engine running efficiently.
