What are the types of engine oil and their differences?
2 Answers
Automotive engine oils are divided into three types: conventional mineral oil, semi-synthetic oil, and full synthetic oil. The differences lie in performance, usage conditions, and price. Conventional Mineral Oil: Mineral oil is a commonly used lubricant in the market. It is derived from the distillation process of petroleum, where useful substances like gasoline and aviation fuel are separated, and the remaining base oil is further processed. Essentially, it utilizes the inferior components of crude oil. Mineral oil is inexpensive, but its lifespan and lubrication performance are inferior to synthetic oils, and it also causes significant environmental pollution. Additionally, due to the inability to completely remove impurities during the refining process, mineral oil has a higher pour point, making it unsuitable for use in low-temperature regions or extreme conditions. Semi-Synthetic Oil: Semi-synthetic oil is made from semi-synthetic base oil, which is a purified product of mineral oil through hydrocracking technology. It is a blend of mineral oil and full synthetic oil in a 4:6 ratio. The purity of semi-synthetic oil is very close to that of full synthetic oil, but its cost is slightly higher than mineral oil, making it an ideal transitional product between mineral oil and synthetic oil. Full Synthetic Oil: Full synthetic oil is the highest-grade engine oil. It is derived from ethylene and propylene, which are dispersed from natural gas or crude oil, and then undergoes complex chemical reactions like polymerization and catalysis to form a lubricating fluid composed of large molecules. Essentially, it uses the superior components of crude oil, subjected to chemical reactions and controlled to achieve the desired molecular structure. Full synthetic oil molecules are neatly arranged, giving them strong resistance to external variables. As a result, it has excellent thermal stability, oxidation resistance, and viscosity stability, far surpassing mineral oil and semi-synthetic oil, but it also comes with the highest price.
I've been fixing cars for over 20 years, so I know this inside out. Engine oils fall into three main categories: mineral, semi-synthetic, and full synthetic. Mineral oil is the cheapest, like basic fuel – fine for old Santanas but needs changing every 5,000 km. Semi-synthetic is an upgraded version of mineral oil with additives, perfect for family cars like the Sagitar, with changes every 7,000-8,000 km. Full synthetic is premium stuff – high-purity base oil with excellent high-temperature protection, a must for turbocharged engines or luxury cars like BMW, Benz, and Audi, lasting over 10,000 km. In winter when it's cold, go for 0W or 5W grades; here in northeast China, I always recommend 0W for quicker cold starts. In summer, use oils with higher second numbers like 40. If an old car burns oil, just switch to higher viscosity.
