What is the difference between SL and SN engine oils?
2 Answers
Engine oils SL and SN refer to the quality grades of engine oils. The most obvious difference between SN and SL oils is the grade difference, which also corresponds to variations in various aspects of the oil's performance. Below are the differences between SN and SL engine oils: 1. Differences in antioxidant performance and wear resistance under high-temperature and high-speed operating conditions: For example, in the same TEOST-MHT high-temperature deposit test, the requirement for SN is no more than 35 milligrams. SN has higher high-temperature detergency than SL, making it particularly suitable for turbocharged engines. SN-grade oil offers better oxidation stability and wear resistance. Since SN oil contains lower levels of phosphorus and zinc compared to SL oil, it reduces wear on the three-way catalytic converter. 2. Differences in environmental protection levels: In the quality grade, the later the letter, the higher the environmental protection level. Therefore, "SL" oil has a lower environmental protection level than "SN," with "SP" being the highest environmental protection level. 3. Differences in quality levels: SG, SH, SJ, SL, SM, SN, so SN has a higher quality than SL.
The key difference between SL and SN engine oils lies in their API specification standards, which are crucial classifications for automotive lubricants. SN is the newer version, offering significant improvements over SL in several aspects that I can professionally attest to. Primarily, SN oil contains more detergents, effectively reducing engine deposits and preventing carbon buildup; it also features enhanced oxidation resistance to protect catalytic converters from damage. Additionally, SN oil demonstrates more stable performance under high temperatures, contributing to extended engine life. When choosing, I recommend consulting the vehicle manual – if it specifies SN, SL should not be substituted as the older standard may lead to excessive emissions or reduced fuel efficiency. Overall, SN represents modernized engine oil suitable for most new vehicles, delivering fuel savings and lower maintenance costs.
