Which is of higher grade, SN or SM engine oil?
1 Answers
SN grade engine oil has a higher quality level, while SM grade engine oil has a lower quality level. Engine oil grades are classified as SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, and SN, with the grade increasing as the letters progress further in the alphabet. SN can replace SA-SM grade engine oils, but SM cannot replace SN grade engine oil. The differences between SN and SM engine oils are as follows: Different types of engine oil: In the classification of engine oils, SN grade engine oil is mainly composed of full synthetic oil, while SM grade engine oil is primarily semi-synthetic oil. Different environmental protection levels: SN grade engine oil has a higher environmental protection level; SM grade engine oil has a lower environmental protection level. Different high-temperature detergency: SN engine oil has higher high-temperature detergency than SM. SN grade engine oil provides better piston cleanliness, high-temperature deposit control, and low-temperature sludge control performance, meeting the performance requirements of the engine under various operating conditions. Different oxidation stability and anti-wear properties: SN grade engine oil has higher oxidation stability and anti-wear properties. This is because SN engine oil contains lower levels of phosphorus and zinc compared to SM engine oil, reducing wear on the three-way catalytic converter and thus enhancing the performance of the engine oil.
