Select Synthetics

Service Classifications (in North America) are determined by the American Petroleum Institute (API), while oil viscosity grades are determined by the Society of Automotive Engineers (SAE). They are divided into two categories: "S" categories and "C" categories. The "S" (Service / Spark Ignition) classifications are for oils designed for gasoline engines; the "C" (Commercial / Compression Ignition) classifications are for oils designed for diesel engines or commercial vehicles.

“API’s Engine Oil Licensing and Certification System (EOLCS) is a voluntary licensing and certification program that authorizes engine oil marketers that meet specified requirements to use the API Engine Oil Quality Marks. Launched in 1993, API’s Engine Oil Program is a cooperative effort between the oil and additive industries and vehicle and engine manufacturers Ford, General Motors, and Fiat Chrysler and those represented by the Japan Automobile Manufacturers Association and the Truck and Engine Manufacturers Association. The performance requirements and test methods are established by vehicle and engine manufacturers and technical societies and trade associations such as (ASTM), (SAE), and the American Chemistry Council (ACC).

The Engine Oil Program is backed by a monitoring and enforcement program that ensures licensees adhere to program requirements. This includes running physical, chemical, and performance tests on licensed engine oils and verifying that the API-registered Marks are properly displayed on containers and convey accurate information to consumers. About half of the program’s licensees are based in the United States, and the other half are spread around the globe.” api.org

In other words, the Licensee pays a Licensing Fee to API which then entitles them to use the coveted API Service Symbol "Donut" on the back label of their Motor Oil as well as the API Certification Mark, also known as the "Starburst" on the front label. (see below) The API 'Starburst' Certification Mark is designed to identify engine oils recommended for a specific application (such as "FOR GASOLINE ENGINES").

The API "Shield" (see above) is a certification mark introduced by the American Petroleum Institute (API) to identify engine oils meeting the strict ILSAC GF-6B standard, which requires superior fuel economy and engine protection, specifically for 0W-16 viscosity grades. It is visually distinct from the older "Starburst" symbol.

An API license indicates that a specific motor oil formulation has passed the minimum performance standards as defined by a series of laboratory bench, physical, chemical and engine tests. While the licensed motor oil must meet the established minimum for performance under a specified API Category, other than this minimum performance requirement, there is no differentiation in any product that exceeds the minimum.

The latest API spec for gasoline vehicles is API SQ (see below), which was officially introduced with a first licensing date of March 31, 2025. It replaces the previous API SP standard, offering improved fuel efficiency and better protection against low-speed pre-ignition (LSPI), with backwards compatibility for older engines.

• Launch Date: Licensing began March 31, 2025.
• Combined Standard: It was introduced alongside ILSAC GF-7, which serves as the next-generation specification for passenger car engine oils.
• Key Improvements: Offers enhanced protection against Timing Chain Wear, low-speed pre-ignition (LSPI), and improved fuel efficiency (up to 16% better in certain tests) compared to previous standards.
• Backward Compatibility: API SQ oils are designed to be backward compatible with GF-6 / SP applications.

ILSAC stands for International Lubricants Standardization and Approval Committee. It was formed in 1992 by AAMA (American Automobile Manufacturers Association - representatives of DaimlerChrysler Corporation, Ford Motor Company and General Motors Corporation) and JAMA (Japan Automobile Manufacturers Association) to define the need, parameters, licensing and administration of lubricant specifications.

Together with the Tripartite system (API, SAE and ASTM) they formed EOLCS, the Engine Oil Licensing and Certification System. ILSAC oils often carry the API Service Symbol ('Donut') including the Energy Conserving designation and/or API Certification Mark ('Starburst' or 'Shield').

The latest ILSAC spec is GF-7, which began licensing on March 31, 2025. Designed for modern gasoline, turbocharged, and hybrid engines, ILSAC GF-7 offers enhanced fuel efficiency, better deposit control, and superior protection against Low-Speed Pre-Ignition (LSPI) compared to the previous GF-6 standard. GF-7 oils are designed to be backward compatible with previous ILSAC specs.

The reason GF-7 oils were developed is because of the rapid evolution of engine technology. According to Dr. Michael Warholic, global technology director, Valvoline Global Operations, a key area of concern addressed by the GF-7 standard is engine deposits. “They lead to bigger issues like ring sticking. The OEMs are still seeing this as a top problem,” Warholic explains.

GF-7 raises the bar by tightening deposit limits and lowering wear tolerances on timing chains – helping prevent fuel economy losses and check engine lights caused by even minor timing discrepancies. There’s also a cold-start performance upgrade. GF-7 reduces maximum low-temperature viscosity (MRV) from 60,000 to 40,000 centipoise. Translation: Better oil flow when starting up, when the engine is most vulnerable.

Like its predecessor, GF-7 is split into two categories: GF-7A for most modern gasoline engines and GF-7B for low-viscosity formulations like 0W-16, commonly used in vehicles from Japanese OEMs like Toyota. The key takeaway? GF-7 oils are fully backward compatible.

ILSAC GF-7 engine oil uses two API certification symbols: the "Starburst" (API Certification Mark) for GF-7A and the "Shield" for GF-7B (specifically for SAE 0W-16). These symbols indicate improved fuel economy, better piston deposit control, reduced timing chain wear, and enhanced low-speed pre-ignition (LSPI) protection.

• ILSAC GF-7A (Starburst Mark): Fits standard viscosity grades like 0W-20, 5W-20, 5W-30, etc. It is backward-compatible with GF-6A, GF-5, and older.
• ILSAC GF-7B (Shield Mark): Reserved exclusively for SAE 0W-16 viscosity grades to indicate enhanced fuel economy benefits.
• API SQ Service Symbol (Donut): Alongside the Starburst or Shield, bottles will display the API "Donut" marked with "SQ" to indicate the new service category.

ACEA stands for Association des Constructeurs Européens d'Automobiles (or European Automobile Manufacturers' Association in English). ACEA is the 'European Standard' for motor oils. It is the main lobbying and standards group of the automobile industry in the European Union.

ACEA, was founded in 1991. The founders of ACEA were the 15 most significant European car manufacturers – BMW, DAF, Daimler-Benz, FIAT, Ford, General Motors Europe, MAN, Porsche, Renault, Rolls Royce, Rover, Saab-Scania, Volkswagen, Volvo Car, and AB Volvo. In recent years, the organization has welcomed a wide range of non-European motor vehicle manufacturers with production facilities and research centers in the European Union.

ACEA is involved in a wide range of activities, and defining European oil standards is one of them.

ACEA defines specifications for engine oil's "ACEA Oil Sequences". The ACEA Oil Sequences are updated every few years to be in line with the latest developments in engine and lubricant technology. Namely, the organization issues new oil specifications every time new emissions regulations are introduced by the EU or new engine oil technologies are created.

Even though ACEA sets standards for European oils to meet, it does not approve them. Oil manufacturers may make performance claims for their products if those satisfy the relevant requirements.

Every ACEA specification is made of a letter or letters that indicate the class and a number that defines the category. There are separate categories for oils with different purposes or for different applications within the same class. There are ACEA specifications for passenger car motor oils (the A/B class) for catalyst compatible motor oils (the C class) and for heavy duty diesel engine oils (the E class). The classes are further divided into categories to meet the requirements of different engines.

All A/B oils are stable, stay-in-grade lubricants, used by gasoline engines and light-duty diesel engines. All products belonging to this category are utilized in high-performance petrol engines and light-duty diesel engines.

• A1/B1 oils are low-friction, low-viscosity oils with a high temperature/high shear rate viscosity.
• A3/B3 oils are used for extended drain intervals and severe operating conditions.
• A3/B4 oils are used in high-performance and direct-injection diesel engines. They can also be used instead of A3/B3-grade oils.
• A5/B5 oils are low-friction, low-viscosity oils with a high temperature/high shear rate viscosity.
• A7/B7 oils have an HT/HS viscosity of 2.9 to 3.5 mPas. They offer low-speed pre-ignition and anti-wear protection for turbocharged gasoline DI engines and turbocharger compressor deposit protection for modern DI diesel engines.

According to ACEA, C-grade oils are stable, low-friction, and low-viscosity oils. They are used in vehicles equipped with diesel particulate filters (DPFs) and three-way catalytic converters (TWCs). C-grade oils are also used in high-performance diesel and petrol (gasoline) engines that require the use of oils with low levels of SAPS (Sulfated Ash, Phosphorus, and Sulfur) content.

Based on the amount of the SAPS content, C-grade oils can be low-SAPS and mid-SAPS. C1 and C4 are low-SAPS oils, while C2, C3, C5, and C6 are mid-SAPS oils.

Low-SAPS oils have a lower level of ash content than mid-SAPS oils and are designed to meet the needs of sensitive after-treatment devices. Since low-ash oils cannot be used interchangeably, it is essential to select the product suitable for your car’s engine type.

API CK-4 and FA-4 are 2017+ heavy-duty diesel oil standards. CK-4 is backward-compatible with older engines and designed for robust protection. FA-4 has lower high-temperature, high-shear (HTHS) viscosity for improved fuel economy in new, on-highway engines. CK-4 is widely used, while FA-4 requires OEM approval.

• Compatibility: CK-4 is backward compatible with CJ-4, CI-4+, and CI-4. FA-4 is NOT backward compatible with older engines, designed for 2017+ designs.
• Viscosity & Fuel Economy: FA-4 uses lower viscosity (lower HTHS, 2.9-3.2 cP) to reduce friction and improve fuel economy by 1% to 2%. CK-4 maintains higher HTHS (min 3.5 cP) for traditional protection.
• Performance: Both improve oxidation resistance, shear stability, and aeration over previous standards, but FA-4 focuses on fuel efficiency, while CK-4 focuses on durability for all applications.
• Identification: FA-4 oil "donuts" feature a shaded red portion for differentiation.

Engine oils in this category are heavy-duty oils. Based on their properties, they are further classified into:

• E2 are general-purpose engine oils. They were used in naturally aspirated and turbocharged diesel engines, as well as in medium to heavy-duty applications. This oil type was discontinued in 2010.
• E4 engine oils are stable, stay-in–grade lubricants. They are used for extended oil drain intervals in synthetic vehicles. They are specifically designed to meet Euro 3, Euro 4, and Euro 5 engine emission requirements.
• E6 oils are in line with Euro 4, Euro 5, and Euro 6 engine emission requirements. The chemical limits for these engine oils allow them to be used with particulate filters and SCR NOx reduction systems.
• E7 oils are suitable for Euro 3, Euro 4, and Euro 5 emission diesel engines in severe heavy-duty applications and extended drain intervals.
• E9 engine oils are designed for Euro 4, Euro 5, and Euro 6 emission diesel engines. It is suitable both for engines with and without the diesel particulate filter.
• E11 oils replace E9 oils. Those are super-high-performance mid-SAPS diesel oils (SHPD). With the HT/HS lower than 3.5 mPas, they are suitable for diesel engines with diesel particulate filters.

Although it is true that the performance standards and requirements to meet the ACEA specs tend to be higher and more stringent than the minimum requirements set by API, as I mentioned before, many high quality synthetic oils available in North America do in fact meet the European ACEA specs.

What is an OEM motor oil specification? An OEM motor oil specification is an interface between an oil's physical and chemical properties and the car manufacturer's requirements. Car manufacturers combine a set of expected properties and test results in a specification while oil companies have their products tested for those requirements and show the earned specification or "approval" on the product as proof that their product is fit to be used where that particular spec is demanded.

Some car manufacturers will actually run very specific engine tests to make sure the oil used meets the specific requirements of their vehicles - these tests are in addition to those required by API or ACEA (which are minimum specs). Those OEMs will subsequently come out with a list of "approved motor oils" to be used in a specific vehicle.

So OEM oil specs are codes, which are used to match oils with cars. By choosing an oil based on a specification we make sure that we choose the right oil for our car.

To achieve full approval, lubricant manufacturers typically submit an oil sample to the OEM for testing, to ensure it complies fully with the specification. Testing is carried out by an independent laboratory or, in some cases, by the OEM themselves. If the oil is fully compliant, the OEM issues a "certificate of approval" that usually lasts between one and five years. This certificate proves that the lubricant has undergone a rigorous approval and quality control process.

Note: Some manufacturers (i.e., KIA, Hyundai, Toyota) don't have an "OEM specific" certification or "approval" and only recommend a minimum API, ILSAC, and/or ACEA requirement that the motor oil should meet.

Why all the different OEM oil specs? Some are recommended for gasoline powered cars, others for diesels; some are for newer cars, some for older; some are for normal drain intervals, some are for extended drains. This means that not all of them demand similar performance levels from the motor oil.

There are higher end standards and lower end standards and it's good to know which one to choose if you want an oil that excels in as many areas as possible.

European vehicle manufacturers have strict guidelines concerning oil requirements for each engine type. Each car brand, including Fiat, Renault, Volkswagen, Audi, Ford, and BMW has detailed oil specifications for different types of their engines. (The chart below lists some of these OEM specs.)