What do the letters in "SAE 10W-30" motor oil signify?

The designation "SAE 10W-30" refers to a specific classification of motor oil established by the Society of Automotive Engineers, commonly abbreviated as SAE. The "10W" indicates the oil's viscosity at low temperatures, where the "W" stands for winter. This signifies that the oil flows like a 10-weight oil when cold, ensuring adequate lubrication during cold starts. The "30" represents the oil's viscosity at higher temperatures, indicating that it has the thickness of a 30-weight oil when the engine is at operating temperature. This classification helps consumers select the appropriate oil for their vehicles based on climate and driving conditions. The other options do not accurately represent the organization responsible for this standard or the meaning behind the viscosity rating.