Can Semi-Synthetic Engine Oil Be Used for One Year?

[StKendra]

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.

[VonEvan]

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.

[Brenda]

As a long-time car owner who has driven for over a decade, I must say that while semi-synthetic oil theoretically lasts 12 months, my personal experience has proven otherwise on multiple occasions. For instance, in my heavily congested city where my daily commute takes less than half an hour, the engine often doesn't reach optimal temperature. This leads to moisture retention and oil deterioration. Combined with extreme winter cold and summer heat accelerating oxidation, I've noticed power loss and increased fuel consumption after just half a year of use. One time when I pushed it until year-end, the engine developed abnormal noises requiring emergency repairs. Therefore, it's better not to gamble - replace the oil promptly when either the time or mileage limit is reached. This becomes especially crucial if you frequently take family trips on highways, as oil failure could cause unexpected breakdowns compromising safety. My advice? Stick to regular maintenance - the peace of mind far outweighs the small savings you might get from delaying oil changes.

[DeDiana]

Friend, I understand you want to save money. Semi-synthetic oil is relatively cheaper, and I've personally tested it—it might last a year in an ordinary car, but it's not necessarily reliable. The key factor is your driving conditions. For example, if you frequently drive short distances in the city, the oil deteriorates faster. If you mostly drive long distances on highways, it might last longer, but the oil quality will still degrade—like turning black and losing lubricity. This could lead to minor engine wear or even the risk of failure. I once tried running it for over 20,000 kilometers, but a later inspection revealed a lot of sludge, making repairs more troublesome. It's better to stick to the conventional practice of changing it every six months or 7,000–8,000 kilometers. It’s simpler and more cost-effective in the long run—just skip a few cups of milk tea, and you’re covered.