What Are the Types of Automotive Engine Oil?
3 Answers
Automotive engine oils can be categorized into fully synthetic, semi-synthetic, and mineral oil types. Semi-synthetic oil is produced by cracking mineral oil and then synthesizing it, resulting in a more consistent chemical composition. Due to its high refining cost, it is relatively expensive, but it offers excellent oxidation resistance, making it a high-quality long-lasting engine oil with a service life of approximately twelve months. Automotive engine oil serves as a lubricant for the engine. Since engine components are made of metal, without lubrication, metal-to-metal friction can easily cause irreversible damage to the parts. Therefore, engine oil is essential to form a protective oil film on the components, ensuring lubrication and protection.
Automotive engine oils are mainly divided into three categories, and I've personally tried them all after driving for over a decade. Mineral oil is the cheapest, like Shell Helix HX3, with base oil directly refined from crude oil. It typically needs replacement every 5,000-6,000 km, thinning easily in summer heat and thickening like syrup in winter. Semi-synthetic oil contains chemical additives, such as Castrol GTX Magnatec, offering moderate performance and price, and can last 7,000-8,000 km between changes. Full synthetic oil is the most expensive but hassle-free, like Mobil 1, resulting in quieter engine operation, faster cold starts, and lasting over 10,000 km. Choosing oil also depends on viscosity and API ratings: 5W-40 for older cars to resist wear, while 0W-20 is recommended for newer cars for fuel efficiency.
From a maintenance perspective, engine oils are categorized into three types based on their base oils. Mineral oils are cost-effective but have poor thermal stability, making them prone to oxidation during high-speed driving in summer. Semi-synthetic oils, like Great Wall Golden Shell, blend synthetic base oils with mineral oils and are suitable for daily commuting in mid-to-low-end vehicles. Fully synthetic oils use entirely chemically synthesized base oils, offering superior fluidity and wear resistance, making them essential for turbocharged German cars. In oil viscosity grades, the number before "W" indicates low-temperature fluidity—0W starts faster than 5W in winter. The number after "W" represents high-temperature viscosity, with SUVs typically choosing 30 to 40. Using the wrong oil may trigger the engine warning light.
