What is the difference between SN and SL engine oil?
4 Answers
SN-grade engine oil has a higher classification than SL. The API classification represents the quality grade of engine oil. It uses a simple code to describe the working capability of engine oil. Engine oil grades are divided into SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, and SN levels. The later the letter in the alphabet, the higher the grade, with SN being the highest-grade engine oil currently available. Below is a related introduction: 1. Introduction to engine oil: Engine oil, also known as engine lubricant, has a density of approximately 0.91×10³ (kg/m³). It serves to lubricate and reduce friction, assist in cooling, seal and prevent leaks, prevent rust and corrosion, and act as a shock absorber for the engine. It is hailed as the 'blood' of automobiles. 2. Composition of engine oil: Engine oil consists of two parts: base oil and additives. The base oil is the main component of lubricating oil, determining its basic properties, while additives can compensate for and improve the shortcomings of the base oil's performance, granting it new properties. Additives are an important component of lubricating oil.
I've been running a repair shop for many years and have seen plenty of oil-related issues. Both SN and SL are API oil classification standards, but SL is an older version, roughly the 2001 standard, which has largely been replaced by SN nowadays. The SN grade primarily offers upgraded emission compatibility, providing better protection for catalytic converters to prevent exhaust emissions from exceeding environmental test limits; it has superior anti-wear properties to extend engine life; and it also improves fuel economy, making highway driving more fuel-efficient. For older vehicles, say pre-2005 models, SL may still be usable, but modern cars should use SN – otherwise, the engine warning light might come on. Always check the owner’s manual when changing oil; don’t cut corners to save money. Remember, SN has broader compatibility and supports modern engine technologies.
I usually enjoy researching car maintenance, and choosing the right engine oil is crucial. The difference between SN and SL lies in the time gap and functional upgrades: SL is an earlier standard, designed without considering today's high emission requirements; SN is a newer version, focusing more on environmental friendliness and engine protection. For example, SN can prevent excessive phosphorus content from damaging the catalytic converter, which is important for city driving where environmental inspections are common; its anti-wear technology is more advanced, especially for turbocharged vehicles. It's recommended to use SN oil for regular vehicles, particularly those manufactured after 2010. While SL oil might be cheaper, the risks are higher, potentially causing engine noise or vibrations. Get into the habit of checking packaging labels, and if unsure, consult a professional shop.
As a seasoned driver, I've encountered situations where using the wrong engine oil led to needing a tow. Simply put, the difference between SN and SL oils is that SL is outdated while SN is better. SL only provides basic engine protection, whereas SN improves emission control to prevent catalytic converter clogging and enhances high-temperature wear resistance, making it more reliable for long highway drives. Older cars can still use SL, but newer models may frequently trigger fault codes if SL is used. Just check if the API symbol on the oil bottle is clear—SN is usually marked more prominently. Additionally, SL oil is cheaper, but engine repairs cost more, making it not worth it. In short, always prioritize SN for safety and peace of mind.
