What is the difference between semi-synthetic and conventional motor oil?
4 Answers
Motor oils commonly used can be categorized into three types based on their base oils: mineral oil, semi-synthetic oil, and full synthetic oil. The primary difference among these three types lies in the base oils used. More details are as follows: 1. Mineral oil is derived from the residual inferior materials after petroleum refining, processed through hydrocracking to obtain the base oil. The biggest advantage of mineral oil is its low cost, making it the most affordable and widely used. However, mineral oil also offers the poorest lubrication performance. 2. Full synthetic oil is made from high-quality raw materials such as natural gas, olefins, soft wax, and premium mineral oil, processed using synthetic technologies like PAO, XVHl, VHV, GTL, and XTL. Due to the superior raw materials and technology used, full synthetic base oils outperform mineral oils in longevity, low-temperature fluidity, oxidation resistance, high-temperature shear resistance, noise reduction, and cleanliness. However, they are more expensive. 3. Semi-synthetic oil is essentially a blended oil, formulated by mixing full synthetic base oil and mineral oil in a certain ratio. This allows semi-synthetic oil to perform closer to full synthetic oil while maintaining a moderate price, serving as a transitional product between mineral oil and full synthetic oil. 4. Naturally aspirated engines can use any type of oil, whereas turbocharged engines require either semi-synthetic or full synthetic oil. This is because turbocharged engines have higher demands on oil quality, necessitating the use of synthetic oils. The choice should be based on actual conditions.
The main differences between semi-synthetic oil and conventional oil lie in their composition and performance. Semi-synthetic oil is a blend of mineral oil and synthetic oil, offering greater stability in high-temperature environments, smoother engine operation, and reduced noise—especially noticeable during prolonged summer driving when the engine feels less strained. In contrast, conventional oil is purely mineral-based, significantly cheaper but prone to thinning at high temperatures, leading to diminished protective properties and potentially increased engine wear. Additionally, semi-synthetic oil allows for longer oil change intervals, typically lasting 7,000 to 10,000 kilometers, whereas conventional oil requires checks around every 5,000 kilometers; otherwise, the car may experience more pronounced vibrations. Long-term use of semi-synthetic oil also helps reduce carbon buildup, making it particularly beneficial for older vehicles. However, using conventional oil in new cars isn’t a major issue—it largely depends on your driving habits.
From my personal experience, semi-synthetic oil performs significantly better than conventional oil in terms of cleaning performance. By blending synthetic materials, semi-synthetic oil can more effectively dissolve impurities in the engine, keeping components cleaner and reducing sludge buildup, which helps extend my car's lifespan. While conventional oil is more budget-friendly and provides basic protection, its fluidity suffers in cold winter temperatures, making the engine struggle during cold starts, and it's prone to oxidation and degradation in high summer temperatures. During oil changes, I can clearly observe that semi-synthetic oil leaves less residue, and the oil filter lasts longer. However, for those who don't drive much for daily commuting, conventional oil is sufficient. Overall, I'd recommend semi-synthetic oil for frequent highway driving or extreme weather conditions, whereas conventional oil is more cost-effective for short-distance, gentle driving.
The main differences between semi-synthetic oil and conventional oil lie in cost and durability. Semi-synthetic is more expensive, costing over 200 yuan per change for my household use, but it has a much longer service interval—it remains stable even with an annual change at around 10,000 kilometers. Conventional oil is cheaper at just over 100 yuan, but requires changes every 3,000 to 5,000 kilometers, making maintenance more troublesome and time-consuming. Performance-wise, semi-synthetic oil is more reliable under extreme temperatures, causes less engine wear, and suits frequent travelers like me. Conventional oil meets basic needs but may cause issues in older cars. The choice depends on budget and driving frequency: semi-synthetic for long-term peace of mind, conventional for short-term savings.
