Can Semi-Synthetic Engine Oil Be Used for One Year?
2 Answers
Semi-synthetic engine oil is not recommended for use over one year. Generally, mineral oil should be replaced every 3 months or 5,000 kilometers, semi-synthetic oil every 6 months or 7,500 kilometers, and full-synthetic oil every 12 months or 10,000 kilometers. Below are specific methods for selecting engine oil for your car: 1. Performance selection: If you prioritize the longevity of the oil, you can choose Mobil oil; if you focus on the oil's cleaning ability for the engine, Shell lubricants can be used; if you need lubricants with strong oil film toughness, Castrol is recommended. 2. Driving conditions: For frequent driving in congested areas, older vehicles, or long-distance heavy-load transportation, the viscosity of the lubricant can be appropriately increased. 3. Engine type: For naturally aspirated engines, mineral oil and semi-synthetic oil can be used. Compared to naturally aspirated engines, turbocharged engines have a more compact structure and operate under harsher conditions, requiring higher-grade lubricants with better fluidity, preferably full-synthetic oil.
When I usually help friends with car repairs, I often see similar issues. Whether semi-synthetic oil can last a year mainly depends on your driving habits and environment. Generally, manufacturers recommend changing it every 6 to 12 months, but you shouldn’t rigidly stick to the timeline because the oil will degrade over time even if the car isn’t driven much. This is especially true under harsh conditions—like frequent short trips where the engine doesn’t reach optimal temperature, causing moisture buildup in the oil and reduced performance, or in dusty areas where contaminants can thicken the oil and diminish its lubricating properties. I’ve seen cases where someone tried to save money by delaying the change for a year, only to end up with loud engine noise and severe wear, leading to much costlier repairs. So, for safety, it’s best to combine time with mileage control. For example, check the dipstick around 10,000 km to assess the oil’s color and viscosity. If it’s opaque or has a burnt smell, don’t push it—change it early to avoid bigger problems.
