What is the difference between SN and SM engine oil?

[JadeAnn]

Differences between SN and SM engine oil: 1. Different effects: SM engine oil has excellent oxidation resistance and is more wear-resistant; SN engine oil has strong cleaning ability and makes vehicle emissions more environmentally friendly. 2. Different environmental protection levels: Engine oils are classified by environmental protection level, with higher letters indicating higher environmental protection standards. SN engine oil has a higher environmental protection level than SM. Engine oil, also known as engine lubricant, serves functions such as lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion prevention, and shock absorption. 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 compensate for and improve the shortcomings of the base oil, providing certain new properties, making them an important part of lubricating oil.

[DiNatalie]

I often help friends with car maintenance and have been paying attention to engine oil for years. Simply put, SN is an upgraded version of SM. The API introduced SN in 2010 to replace SM from 2004. The key differences are: SN focuses more on environmental protection, reducing phosphorus content to below 0.08% to prevent contamination of exhaust catalytic converters, while SM has higher phosphorus levels; SN has better oxidation resistance, making the oil less prone to thickening due to oxidation, thereby extending its service life and change intervals; it also improves fuel economy, especially providing better support for modern turbocharged engines. Compared to SM, SN can reduce engine sludge deposits, making the car run smoother. If your car was purchased in recent years, I definitely recommend using SN oil—it matches the new emission standards and is safer. Since I started using SN, my engine runs smoother, and I've had fewer maintenance issues. Never skimp by using the outdated SM grade—it's obsolete, and using it in new cars may affect performance and longevity.

[PaigeDella]

When getting my car serviced, I'm always asked whether to choose SN or SM engine oil. The truth is SN is newer and stronger in design than SM. SM is a 2004 standard, basically meeting the needs of older engines; SN was upgraded in 2010, adding phosphorus limits to protect emission systems and reduce the risk of catalytic converter clogging. Its oxidation resistance is improved, so the oil doesn't age and turn black as easily, making it suitable for high-temperature driving. There's also a slight improvement in fuel economy, saving some money on gas. Modern car engines are better suited for SN because it handles high pressure better, such as in turbocharged vehicles. Using SM might save money in the short term, but in the long run, SN is more worry-free for maintenance. I recommend car owners choose oil according to the manual: new engines specify SN, while older cars can temporarily use SM as a transition but should eventually upgrade. Don't neglect the oil change interval, and regularly check the grade to ensure compatibility.

[DeCarlos]

I'm researching the differences between engine oils for my new car. Both SN and SM are API classifications, with SN introduced in 2010 to replace the older SM standard. Key improvements: SN reduces phosphorus content below 0.08% to better protect exhaust treatment systems from failures; enhances oxidation resistance to slow oil breakdown; and provides more stable support for modern engines like turbocharged ones. Compared to SM, SN better meets emission requirements for newer vehicles. For daily driving, using SN oil can reduce carbon buildup and sludge while improving engine responsiveness. Although both are usable, SN's updated formulation makes it the smarter choice for cost and convenience. Most modern engine oils on the market are SN-rated—just check the label for quick identification.