Is SL or SN engine oil better?

[VonGemma]

SN engine oil is better. The classification levels of engine oil are SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, and SN. The later the letter in the alphabet, the higher the grade. Engine oil is engine lubricant, composed of base oil and additives, with base oil being the main component. The functions of engine oil are: 1. To separate the surfaces of relatively sliding parts, thereby reducing wear; 2. To bring heat back to the oil tank and then dissipate it into the air to help the radiator cool the engine; 3. To circulate carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank, flushing away dirt generated on the working surfaces of parts through the flow of the lubricating oil.

[Shelly]

As a driver with over a decade of experience, I believe choosing engine oil depends on your car model. Having transitioned from an older vehicle to a newer one, I found that SL-grade oil works perfectly fine for older cars—it's cost-effective and meets basic lubrication needs. However, for newer models, especially those produced after 2010, SN-grade oil clearly performs better. It offers superior anti-wear protection and ensures smoother engine operation. After switching to SN oil myself, I noticed significant improvements in fuel efficiency and reduced engine noise, thanks to its advanced formulation. Long-term use of SN oil can also extend engine life and lower maintenance frequency. Always check your owner’s manual, which typically specifies the recommended oil type. Also, consider viscosity matching during seasonal changes to ensure smooth driving year-round. Overall, SN is the go-to for newer cars, while SL remains a budget-friendly option for older vehicles if needed. Most importantly, stick to regular oil changes—timing matters more than brand loyalty.

[SanArabella]

I've always been fascinated by automotive technology and have done in-depth research on the evolution of API engine oil standards. Both SL and SN are classification levels, with SN being the newer standard introduced after 2011. It features upgraded multiple tests, such as stricter control over engine deposits and phosphate content limits, which help reduce harmful emissions and benefit environmental protection. SL is relatively older with simpler technology, but it still works fine for older vehicles. In practical applications, SN oil can improve fuel economy by approximately 2%-3%, which is quite noticeable in daily driving. I've also tested different driving conditions and found that SN oil better protects piston rings from wear during frequent start-stop cycles in urban areas. If you drive a hybrid or a turbocharged engine, SN is essential as it's compatible with modern designs. Don't just focus on the classification; also consider viscosity grades like 5W-30 to ensure stable performance across various temperatures. For daily operation, I recommend prioritizing SN oil for its better cost-performance ratio and potential compliance with stricter emission regulations in the future.

[LeWilliam]

Driving is all about convenience and cost savings, so I consider the actual cost when choosing engine oil. SL-grade oil is significantly cheaper and is perfectly adequate for older cars or those with over 100,000 kilometers, helping to avoid unnecessary expenses. On the other hand, SN-grade oil, though pricier, offers better protection for new or high-end vehicles, such as reducing sludge buildup and extending engine life. My personal view is to first check the vehicle’s manual—it will tell you which oil is suitable. For daily city driving with frequent stops, SN-grade oil can help reduce fuel consumption, making it a worthwhile investment in the long run. If the budget allows, I’d recommend SN-grade oil due to its updated technology and broader compatibility. Don’t overlook the oil change interval—regardless of the grade, replacing it every 5,000 kilometers or six months ensures optimal performance. Seasonal changes also matter; thinner viscosity oil in winter ensures quicker starts. Simply put, new cars should use SN-grade oil, while older ones can stick with SL—the key is maintaining regular upkeep.