The current and previous API Service Categories are summarized in convenient charts. Vehicle owners should refer to their owner's manuals before consulting these charts.

API Service Category CK-4 describes oils for use in high-speed four-stroke cycle diesel engines designed to meet 2017 model year on-highway and Tier 4 non-road exhaust emission …

Aug 25, 2025 · API has introduced a new "SQ" service category, designed to meet the latest requirements of modern turbocharged direct injection engine (TGDI) technology.

Dec 6, 2025 · Choosing the correct category ensures your engine gets the protection it needs against wear, deposits, and sludge, which is crucial for longevity and performance.

The service rating of motor oils is classified by the American Petroleum Institute (API). The program certifies that an oil meets certain OEM quality and performance standards.

Which oil is right for you? The current and previous API Service Categories are listed below. Vehicle owners should refer to their owner's manuals before consulting these charts. Oils may …

Gear oils are classified by the API using GL (Gear Lubricant) ratings. This classification defines the corresponding basic requirements and application conditions and the type of gears most …

The API “S” series describes oil standards primarily for gasoline engines while the API “C” series describes oil standards for diesel engine service. A description of the API service symbol and …

Jan 5, 2026 · This API rating system is the universally recognized method that allows consumers and mechanics to confidently verify the quality and intended use of a specific motor oil before …

This six-page laminated guide is designed to help consumers understand the API Engine Oil Quality Marks—the API Certification Mark "Starburst," the API Certification Mark "Shield" and …