What is the difference between SN and SL engine oil?

[SavannahLynn]

The most obvious difference is the grade level. In engine oil labeling, SL refers to the oil grade. API is the abbreviation for the American Petroleum Institute, and the API grade represents the quality level of engine oil. It uses simple codes to describe the working capability of engine oil. The oil grades range from SA to SN, with each subsequent letter indicating a higher grade. The most obvious difference is the grade level. There are four main differences between SN and SL engine oil: 1. Different antioxidant and anti-wear performance under high-temperature and high-speed operation conditions: In the same TEOST MHT high-temperature deposit test, the SN standard requires no more than 35 milligrams; SN has higher high-temperature cleanliness than SL, making it especially suitable for turbocharged engines. SN-grade oil has higher oxidation stability and anti-wear properties. Since SN oil contains lower levels of phosphorus and zinc compared to SL oil, it reduces wear on the three-way catalytic converter. 2. Different environmental protection levels: Engine oils are classified by environmental protection level, with higher letters indicating higher environmental protection grades. Therefore, SL oil has a lower environmental protection level than SN, and the highest environmental protection level is SN-grade oil. 3. Different grades: The grades are SG, SH, SJ, SL, SM, and SN, so SN has higher quality than SL. 4. The number of SL-grade oils available for sale is fewer than SN.

[LaElaina]

I see significant differences between the API SN and SL motor oil standards. SL is an old 2001 version suitable for vintage car engines with looser emission controls. SN was upgraded in 2010 to optimize fuel economy, reduce phosphorus content to protect catalytic converters, and minimize carbon deposits and wear. Modern engines like turbocharged vehicles perform more reliably with SN-grade oil while saving fuel costs. For daily oil selection, always refer to your vehicle manual's recommendation - avoid using SL-grade in new cars as it may damage catalytic converters, leading to costly repairs. It's best to directly choose SN or the newer SP-grade for better compatibility and easier maintenance, ensuring smoother engine performance.

[MacMadeline]

I think SN engine oil is much more practical than SL. SL is acceptable for older cars, but SN is designed for newer models, with improved cleaning capability to keep the engine interior clean and reduce failure rates. During daily driving, switching to SN oil results in a slight decrease in fuel consumption and reduced engine noise. If SL is improperly used in cars manufactured after 2010, the catalytic converter can easily get clogged, leading to expensive repairs. It's recommended to first check your car's manufacturing year. For cars before 2000, SL can be considered, but otherwise, prioritize SN for safety, cost savings, and peace of mind.

[McPreston]

I believe SN is an improved version of SL, with the main difference being in formulation optimization. SL has lower emission standards and higher phosphorus content, which may harm the catalytic converter; SN enhances environmental protection, reduces emissions, and provides stronger engine protection. Modern vehicles should use SN to avoid deposit buildup and extend lifespan—don't risk increased maintenance costs by using cheaper SL in new cars. Simply put, choosing higher-grade oil ensures smoother engine performance.

[OLiam]

From a cost-saving perspective, SN-grade engine oil is worth the price. It improves fuel efficiency, allowing you to drive the same distance with less fuel consumption. SL-grade oil is cheaper but offers inferior protection, which can easily lead to catalytic converter issues and costly repairs. In the long run, purchasing SN-grade oil saves you money on fuel and reduces maintenance frequency, making the engine more durable and cost-effective.