Short answer
These are marks licensed under API’s Engine Oil Licensing and Certification System (EOLCS). The donut, or API Service Symbol, shows the service category, the SAE viscosity grade and whether the oil is Resource Conserving. The starburst, or API Certification Mark, means the oil meets the current ILSAC standard for its grade, and the shield marks oils meeting ILSAC’s 0W-16 standard.
What EOLCS is
EOLCS is a voluntary program run by the American Petroleum Institute. Oil marketers who want to use the marks sign a license and certify that each product meets the requirements in API 1509, the document that sets out the categories, testing rules and labeling rules.
API also samples licensed oils from the marketplace and tests them against the claims on the label. The online EOLCS directory lists which brands and products hold current licenses.
Reading the donut
The top half of the donut names the service category, such as SQ for gasoline engines or CK-4 for diesel engines; some oils list more than one. The center shows the SAE viscosity grade. The bottom half reads “Resource Conserving” only for gasoline oils in the ILSAC grades that pass the extra fuel economy and emission-system requirements.
The starburst and the shield
The starburst appears on the front of the container and tells a shopper the oil meets the ILSAC standard of the day, now GF-7A, for 0W-20, 5W-20, 0W-30, 5W-30 or 10W-30. API rules do not allow it on 0W-16 oils.
The shield was created for ILSAC’s 0W-16 standard, first GF-6B and now GF-7B. Its separate shape is meant to signal that the oil belongs only in engines that specify 0W-16.
What the marks do not cover
API marks say nothing about automaker approvals such as GM dexos, European ACEA sequences or approvals from Volkswagen, Mercedes-Benz or BMW, or motorcycle standards such as JASO. Those are licensed or approved separately and appear as their own logos or text.
Some oils, including many racing and specialty products, are not made to API categories at all. The absence of a donut does not describe quality one way or the other; it means the product is not licensed under EOLCS.
Frequently asked questions
Can an oil without an API donut be suitable?
It depends on what the engine needs. Licensing is voluntary, and some specialty oils are formulated for uses outside API categories. If the owner’s manual calls for an API category, choose an oil licensed to it.
Where can I check whether an oil is licensed?
API publishes an online EOLCS directory that lists licensed products by company and brand, with the categories each holds.
General maintenance information. Always follow your vehicle or equipment manufacturer’s requirements and the current product data. Questions? Email [email protected].