Oils sold as automotive lubricants are classified according to oil viscosity, or an oil's resistance to flow. The viscosity of oil is measured by how long it takes a set volume of oil to pass through an opening. Thin oils will naturally move through an opening faster than thick oils; thin oils thus have low viscosity. However, since oil viscosity is inversely proportionate to oil temperature, any viscosity rating must include temperature data. For these reasons, the Society of Automotive Engineers (SAE), the professional organization responsible for commercial oil ratings, uses a dual classification system. In the designation 10W-40, for instance, the first number is the oil's cold(winter) viscosity and the second is its operating viscosity in a hot engine.

단어 수준이 어렵긴 해도 수능 지문처럼 비비 꼬고 그렇진 않아. 어디서 개 같은 논문 짜깁기 해서 변별력이라는 허울로 수험생 줄이나 세우냐?

수능 출제 위원 지옥 가라.