What level is SL engine oil?

[Debra]

SL engine oil is a lower-grade classification. In the categorization of engine oils, there is a parameter called the API quality grade. For gasoline engine oils, the grades range from SA to SP. This designation essentially describes the quality of the oil—the further the letter after 'S' is in the alphabet, the higher the performance and quality of the oil. Currently, SP is the highest grade available. Engine oil is a substance enhanced with additives in base oil, primarily containing anti-wear additives, detergents, dispersants, and multi-grade viscosity index improvers. Engine oil is used for lubricating internal combustion engines, with its main functions being to reduce friction and wear on moving parts, remove sludge and varnish from the engine, neutralize acids produced by fuel and lubricant oxidation, improve piston ring sealing, and cool the engine by carrying away heat from moving components.