Which organization classifies oil by its viscosity?

• A. Society of Automotive Engineers
• B. American Petroleum Institute
• C. National Institute of Standards and Technology
• D. International Organization for Standardization

Answer: (A)

The main idea is that engine oil viscosity is labeled by the Society of Automotive Engineers. They created the SAE viscosity grade system used on motor oils, defined in SAE J300. The number before the W indicates cold-start flow (winter performance), and the number after the W indicates high-temperature viscosity. This labeling lets technicians choose oil that will pump well when starting cold and still protect the engine when hot. API, NIST, and ISO handle other aspects like performance standards, precise measurements, or general lubricant standards, but the standard that classifies oil by its viscosity for automotive use is SAE.