SN on motor oil signifies the latest American Petroleum Institute (API) performance classification for gasoline engine lubricants. The "S" designates Spark Ignition engines (gasoline engines), and the "N" represents the specific performance level, the most recent in a series of advancements from SA to SN. This classification indicates the oil meets stringent standards for protection and performance in modern gasoline-powered vehicles. The API continually updates these classifications to keep pace with engine technology. For diesel engines, the API uses a different classification system (e.g., CK-4).
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Understanding the API SN Classification: This designation ensures the oil meets performance requirements set by the API, covering aspects like engine wear protection, deposit control, and fuel economy. Choosing an oil with the SN classification ensures you're using a lubricant that meets the standards for your gasoline engine.
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Evolution of API Classifications: The API SN classification is the latest iteration in a series that has evolved over time, improving performance standards with each new designation. Older classifications like SA and SB are obsolete and no longer meet the demands of modern engines.
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Distinguishing from Diesel Classifications: It's crucial to understand that the API SN classification applies only to gasoline engines. Diesel engines use a different set of classifications, such as CJ-4 or CK-4. Using the wrong type of oil can damage your engine.
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Example: Seeing "SN" on an oil bottle indicates that the oil meets the API's latest performance standards for gasoline engines, offering enhanced protection and performance compared to older classifications.
