API (in terms of engine oil) is an abbreviation of the American Petroleum Institute – this is where the API system was created back in 1947.
There are 3 main types of API classification:
- For powertrain parts.
- For gasoline engines.
- For engines that run on diesel fuel.
API Engine Oil Grade
Meaning of letters
Engine oil standards by API are indicated by a two-letter marking:
- 1st letter: engine type designation – S – gasoline engine, C – diesel engine.
- 2nd letter: quality standard – the further the letter is from the beginning of the alphabet, the higher the quality. The modern standard for gasoline engines is L, for diesel engines it is F.
- Oils of the latest generation can also have a double slash, for example, API SG/CE – it means it is designed for both gasoline and diesel engines.
API classification is a system used by oil companies to rate the quality of their products. The API classification system has three main categories:
- Service Category (SC)
- Resource Category (RC)
- Product Category (PC)
The Service Category is the highest category and is reserved for oils that meet the most stringent requirements. The Resource Category is for oils that meet less stringent requirements, and the Product Category is for oils that meet the least stringent requirements.
API classification is not a measure of an oil’s performance, but rather a way to help companies ensure that their products meet the minimum standards set by the industry. API classification is voluntary, and not all oil companies participate in the system. However, most major oil companies do participate, and the API classification system is widely recognized as the standard for quality in the industry.
What is engine oil API classification
Engine oil API classification is a system used to classify motor oils according to their performance levels. The API system has two parts: the Service Classification System and the Engine Oil Licensing System.
The Service Classification System is a voluntary licensing program that certifies engine oils for use in passenger cars, light-duty trucks, and sport utility vehicles. The program is administered by the American Petroleum Institute (API).
The Engine Oil Licensing System is a mandatory licensing program that certifies engine oils for use in all passenger cars and light-duty trucks. The program is administered by the International Lubricants Standardization and Approval Committee (ILSAC).
Both the Service Classification System and the Engine Oil Licensing System use a set of performance standards to classify motor oils. The standards are designed to measure an oil’s ability to protect engine parts from wear, deposit formation, and oil degradation.
Oils that meet or exceed the performance standards of either the Service Classification System or the Engine Oil Licensing System are said to be “licensed” or “certified.”
The API service symbol (the “donut”) and the ILSAC starburst are two examples of certification marks that appear on motor oil labels. The API service symbol indicates that an oil meets the performance standards of the Service Classification System. The ILSAC starburst indicates that an oil meets the performance standards of the Engine Oil Licensing System.
Not all motor oils are licensed or certified by the API or ILSAC. Some motor oils are not designed to meet the performance standards of either program. These oils are typically referred to as “unlicensed” or “non-certified” oils.
Unlicensed and non-certified oils are not necessarily inferior to licensed and certified oils. They may simply be designed for use in engines that do not require the high level of protection provided by the API or ILSAC standards.
If you are unsure about which oil is right for your engine, consult your owner’s manual or ask a qualified automotive technician.
To learn more, watch the video below about API Classification meaning
API Classification Meaning
Frequently Asked Questions (FAQ)
The highest API rating for oil is SN, which stands for “Service Category” and indicates that the oil has passed all of the necessary performance tests for use in modern engines.