API is the acronym for American Petroleum Institute, which defines a series of minimum requirements lubricants must meet. The API quality level is represented by a code usually consisting of two letters: The first letter refers to the type of engine (S = gasoline and C = diesel).

The API Certification Mark and Service Level Symbol identify the quality of engine oils for gasoline and diesel vehicles.

Why is API Certification important?

API helps us select quality lubricating oils.

The API Certification is important because it helps us recognize which lubricating oils have the adequate quality for use in our cars, trucks and machinery. This is vital because they are extremely expensive equipment.

This certification is important because the product quality is not audited by the manufacturer, but by the most important oil institute worldwide.

¿How to select quality oil?

It is very easy to know if your oil is certified by API. Just check for the API marks on the product label.

The API Certification Mark is also known as “Starburst.”

This mark means that the oil complies with the current regulations for engine protection and with the fuel economy requirements of ILSAC, a common project of American and Japanese car manufacturers. Automakers recommend oils with the API Certification Mark. See the table of


The API “DONUT” (called this way because of its double circle shape). It is also a certification mark, but it contains information specific to the characteristics of the product that is being certified. Its official name is “Service Symbol.”

The API Donut refers to the following aspects:

  1. Quality Level

Engine oils designed for automobiles, vans, and light trucks with gasoline engines are included in the “S” (Service) API categories. Engine oils designed for heavy vehicles and vehicles with diesel engines are included in the “C” (Commercial) API categories. Refer to the tables for gasoline and diesel engine oils on the following pages, for a description of current and obsolete API service categories.

It is the measure of the oil capacity to flow at certain temperatures. The requirements may vary depending on the vehicle. Follow your car manufacturer’s recommendations regarding the SAE oil viscosity grade.

  1. Energy Saving and Fuel Saving

These categories apply to oils for gasoline engine automobiles, vans and light trucks. Extended use of oils with the category “Energy Saving” and “Fuel Saving” can translate into a general fuel saving in the entire fleet of vehicles.

  1. Multiple Quality Levels

Oils designed for diesel engines can also be used in gasoline engines. For identification of these oils, category “C” is included first, followed by category “S.” Category “C” oils have been primarily formulated for diesel engines, and may not provide the required performance suggested in the gasoline engine car manufacturer’s recommendations.

  1. API Service Symbol with CI-4 Plus

The “CI-4 PLUS” designation identifies the oils formulated to provide a superior level of protection against the increase in viscosity due to soot and the loss of viscosity due to shear in diesel engines. When it began to be used, CI-4 PLUS identified CI-4 oils with a superior performance level.


CJ-4 oils provide all the benefits a CI-4 PLUS oil should have. CI-4 PLUS appears on the lower section of the API “Donut” Service Symbol.