What is the difference between SN grade and SL grade engine oil?
3 Answers
Differences between SN grade and SL grade engine oil: 1. Different quality grades: SN grade engine oil is the highest quality grade among engine oils; SL grade engine oil belongs to the upper-middle quality grade. 2. Different phosphorus content requirements: SN grade engine oil has particularly high requirements for phosphorus content, even being phosphorus-free; SL grade engine oil requires phosphorus content not to exceed 0.1%, with very high requirements for phosphorus content. Engine oil, motor oil, or engine lubricant is a substance enhanced with additives in base oil, mainly containing anti-wear additives, detergents, dispersants, and multi-grade oil viscosity index improvers. Engine oil is used for lubricating internal combustion engines. The main functions of engine oil are to reduce friction and wear of moving parts and to remove sludge and varnish from the engine.
I enjoy researching car maintenance, and there's a significant difference between SN-grade and SL-grade engine oils. SN is the newer standard, introduced around 2010, offering better protection than the 2004 SL grade. First, regarding oxidation resistance, SN reduces sludge buildup, keeping the engine cleaner, especially beneficial for turbocharged vehicles. Second, environmentally, SN has lower phosphorus content, protecting the catalytic converter and preventing premature failure of the emission system. It also improves fuel economy, saving some money on gas. In terms of oil change intervals, SN may allow for longer intervals compared to SL, which requires more frequent changes. I recommend always using SN for new cars; while older cars are compatible with SL, upgrading to SN is more cost-effective for long-term engine protection. Don't forget to choose the right viscosity grade—don't just focus on the oil grade.
When I bought my first car, the salesperson emphasized that I must use SN-grade oil. SN is a higher grade than SL, mainly optimized for performance. It offers better fuel efficiency, reduces internal engine friction, provides smoother driving, and more responsive acceleration at low speeds. In terms of environmental protection, SN causes less damage to the emission system, especially since modern catalytic converters are prone to issues—using SL might accelerate wear. While SL is still available, it's outdated, with poor oxidation resistance and a higher risk of sludge buildup. I tried comparing them and noticed a slight drop in fuel consumption. Don’t skimp and recklessly use SL; beginners are advised to choose SN-certified oil and follow the manual’s oil change intervals.
