e.g. API SL / CF SAE 5W40quot ;, wherein: API represents the American Petroleum Institute (abbreviation) Evaluation standard quality level of the oil. S represents the gasoline engine oil. L represents a level, from API SA, SB, SC, SE, SF, SG, SH, SJ, SL, SM letter the more backward, the higher the grade of oil. C represents the diesel oil. F represents the level from API CA, CB, CC, CD, CE, CF, CF-4, CG-4, CH-4, the next letter, the higher the grade of oil.