What is SN Engine Oil?
1 Answers
SN engine oil is classified as the second tier in the API quality grade for gasoline engine oils, with SP being the highest grade. Oils starting with "S" are specifically designed for gasoline engines and are not suitable for diesel vehicles. When selecting engine oil, one should not only consider which vehicles SN-grade oil is suitable for but also take into account its viscosity. Even within the same SN grade, oils can have different viscosity indices. The viscosity level determines the oil's performance under high and low temperatures, with low-temperature fluidity and high-temperature viscosity dictating the oil's applicable range. It's important to note that oils of different grades should not be mixed, as they contain different chemical compositions. Mixing oils may lead to oil degradation, failing to provide adequate lubrication and resulting in component wear. Therefore, if a vehicle owner needs to switch oil grades, the old oil must be completely drained.