What are the motor oil standards?
2 Answers
Motor oil specifications consist of two parts: classification and viscosity rating. The classification is represented by a combination of two letters. Classification standards: The "S" series represents oils for gasoline engines. The specifications generally range from SA to SN (in alphabetical order, excluding SI). Each subsequent letter indicates improved performance over the previous one, with more additives to protect the engine. The later the letter in the alphabet, the higher the quality grade. International brand motor oils are mostly SF grade or higher. The "C" series represents oils for diesel engines. If both "S" and "C" letters are present, it indicates the oil is suitable for both gasoline and diesel engines. Viscosity specifications: The viscosity of lubricating oil is mostly identified by SAE grades, where SAE stands for the "Society of Automotive Engineers." The "W" stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating it can be used in lower environmental temperatures and provides better engine protection during cold starts. The number after the "W" (following the dash) indicates the oil's high-temperature resistance, with higher numbers representing better protective performance at high temperatures.
Engine oil standards are coding systems that identify oil performance, primarily divided into viscosity grades and quality specifications. SAE viscosity, such as 5W-30, where 'W' stands for winter low-temperature fluidity—the smaller the number, the smoother the cold start, while the higher summer number indicates stronger high-temperature protection. API classifications like SN or SP, where 'S' denotes gasoline engines, and newer numbers represent better cleaning and anti-wear performance. The ACEA standard focuses more on European engines, with categories like A5/B5 suited for high-efficiency vehicles. These standards are regulated by industry associations to ensure engine oil can protect engines under various conditions, prolong lifespan, and reduce emissions. Consulting the manual for recommendations is crucial when selecting oil; otherwise, it may lead to increased noise or fuel consumption.
