What is the difference between SN and SL engine oil?
3 Answers
Engine oil SL and SN refer to the quality grades of engine oil. The most obvious difference between SN and SL oil is the grade difference, which also corresponds to variations in various performance aspects of the oil. Below are the differences between SN and SL engine oil: 1. Differences in oxidation resistance and anti-wear performance under high-temperature and high-speed operating conditions: For example, in the same TEOST MHT high-temperature deposit test: The SN standard requires no more than 35 milligrams; SN oil has higher high-temperature cleanliness than SL, making it particularly suitable for turbocharged engines. SN-grade oil offers better oxidation stability and anti-wear performance. Since SN oil contains lower levels of phosphorus and zinc compared to SL oil, it reduces wear on the three-way catalyst. 2. Different environmental protection levels of the oil: In the quality grades, the further the letter is in the alphabet, the higher the environmental protection level. Therefore, SL oil has a lower environmental protection level than SN, and the highest environmental protection level is SP-grade oil. 3. Classification by quality level: SG, SH, SJ, SL, SM, SN, so SN has a higher quality than SL. 4. Difference in availability: The number of SL-grade oils available for sale is fewer than SN.
I've been driving for twenty years and have changed the oil myself many times. The main differences between SN and SL lie in oil lifespan and engine protection. SL is an older standard, introduced around 2000, with weaker oxidation resistance, making it more prone to deterioration under high temperatures, leading to carbon deposits and sludge. SN is newer, becoming popular after 2010, with enhanced anti-wear formulations, especially suitable for modern engines' low-viscosity designs, keeping the oil more stable and cleaner. In practical use, SN can extend the oil change interval slightly and reduce engine noise. If you want hassle-free maintenance, using SN for both new cars or upgraded older cars is better, as it has broad compatibility and won't harm the catalytic converter. Remember, don’t just pick any label—follow the vehicle manual to avoid wasting money on engine repairs.
I care about the environment, so choosing SN over SL for oil changes helps reduce pollution. The SN standard has stricter oxidation control and emission limits, effectively curbing the release of harmful substances like sulfur and phosphorus, thus protecting air and water sources. SL is a relic of the past with fewer environmental requirements. Every time I use SN oil, I notice less foul odor from engine emissions, contributing less to urban pollution. Of course, if you drive an old classic, SL might suffice, but SN is greener and safer—better for leaving a cleaner world for future generations. Check government regulations; nowadays, most new oils are SN-grade, so pay attention to the labeling on bottles to avoid confusion.
