Overview About API’s Engine Oil Licensing
and Certification System (EOLCS)

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 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. A complete list of licensees is available on our licensee directory.

Requirement

The program’s requirements are described in API 1509, Engine Oil Licensing and Certification System. This standard describes the program’s performance requirements, explains the current engine oil service categories, shows how the marks are to be used, and explains the monitoring and enforcement program. Standards referenced by API 1509, such as ASTM D 4485, Standard Specification for Performance of Engine Oils, and SAE J300, Engine Oil Viscosity Classification, also play a critical role in defining the program. These can be purchased through their sponsoring organizations.

Oil Categories

ILSAC Standard For Passenger Car Engine Oils

The current and previous ILSAC standards are listed here. Vehicle owners should refer to their owner’s manuals before consulting these charts. Oils may have more than one performance level.For automotive gasoline engines, the latest ILSAC standard includes the performance properties of each earlier category and can be used to service older engines where earlier category oils were recommended.

Name Status Service
GF-5 Current Introduced in October 2010, designed to provide improved high temperature deposit protection for pistons and turbochargers, more stringent sludge control, improved fuel economy, enhanced emission control system compatibility, seal compatibility, and protection of engines operating on ethanol-containing fuels up to E85.
GF-4 Obsolete Use GF-5 where GF-4 is recommended.
GF-3 Obsolete Use GF-5 where GF-3 is recommended.
GF-2 Obsolete Use GF-5 where GF-2 is recommended.
GF-1 Obsolete Use GF-5 where GF-1 is recommended.

Gasoline Engines

The current and previous API Service Categories are listed here. Vehicle owners should refer to their owner’s manuals before consulting these charts. Oils may have more than one performance level. For automotive gasoline engines, the latest API Service Category includes the performance properties of each earlier category and can be used to service older engines where earlier category oils were recommended.

Category Status Service
SN Current Introduced in October 2010, designed to provide improved high temperature deposit protection for pistons, more stringent sludge control, and seal compatibility. API SN with Resource Conserving matches ILSAC GF-5 by combining API SN performance with improved fuel economy, turbocharger protection, emission control system compatibility, and protection of engines operating on ethanol-containing fuels up to E85.
SM Current For 2010 and older automotive engines.
SL Current For 2004 and older automotive engines.
SJ Current For 2001 and older automotive engines.
SH> Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1996. May not provide adequate protection against build-up of engine sludge, oxidation, or wear.
SG Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1993. May not provide adequate protection against build-up of engine sludge, oxidation, or wear.
SF Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge.
SE Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1979.
SD Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1971. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SC Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1967. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SB Obsolete CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1951. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SA Obsolete CAUTION: Contains no additives. Not suitable for use in most gasoline-powered automotive engines built after 1930. Use in modern engines may cause unsatisfactory performance or equipment harm.

Diesel Engines

(Follow your vehicle manufacturer’s recommendations on oil performance levels)

Category Status Service
CK-4 Current 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 standards as well as for previous model year diesel engines. These oils are formulated for use in all applications with diesel fuels ranging in sulfur content up to 500 ppm (0.05% by weight). However, the use of these oils with greater than 15 ppm (0.0015% by weight) sulfur fuel may impact exhaust aftertreatment system durability and/or oil drain interval. These oils are especially effective at sustaining emission control system durability where particulate filters and other advanced aftertreatment systems are used. API CK-4 oils are designed to provide enhanced protection against oil oxidation, viscosity loss due to shear, and oil aeration as well as protection against catalyst poisoning, particulate filter blocking, engine wear, piston deposits, degradation of low- and high-temperature properties, and soot-related viscosity increase. API CK-4 oils exceed the performance criteria of API CJ-4, CI-4 with CI-4 PLUS, CI-4, and CH-4 and can effectively lubricate engines calling for those API Service Categories. When using CK-4 oil with higher than 15 ppm sulfur fuel, consult the engine manufacturer for service interval recommendations.
CJ-4 Current For high-speed four-stroke cycle diesel engines designed to meet 2010 model year on-highway and Tier 4 non-road exhaust emission standards as well as for previous model year diesel engines. These oils are formulated for use in all applications with diesel fuels ranging in sulfur content up to 500 ppm (0.05% by weight). However, the use of these oils with greater than 15 ppm (0.0015% by weight) sulfur fuel may impact exhaust aftertreatment system durability and/or drain interval. API CJ-4 oils exceed the performance criteria of API CI-4 with CI-4 PLUS, CI-4, CH-4, CG-4 and CF-4 and can effectively lubricate engines calling for those API Service Categories. When using CJ-4 oil with higher than 15 ppm sulfur fuel, consult the engine manufacturer for service interval.
CI-4  Current Introduced in 2002. For high-speed, four-stroke engines designed to meet 2004 exhaust emission standards implemented in 2002. CI-4 oils are formulated to sustain engine durability where exhaust gas recirculation (EGR) is used and are intended for use with diesel fuels ranging in sulfur content up to 0.5% weight. Can be used in place of CD, CE, CF-4, CG-4, and CH-4 oils. Some CI-4 oils may also qualify for the CI-4 PLUS designation.
CH-4 Current Introduced in 1998. For high-speed, four-stroke engines designed to meet 1998 exhaust emission standards. CH-4 oils are specifically compounded for use with diesel fuels ranging in sulfur content up to 0.5% weight. Can be used in place of CD, CE, CF-4, and CG-4 oils.
CG-4 Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 2009.
CF-4 Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 2009.
CF-2 Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 2009. Two-stroke cycle engines may have different lubrication requirements than four-stroke engines, so the manufacturer should be contacted for current lubrication recommendations.
CF Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 2009. Later “C” category oils are usually suitable or preferred for diesel automotive engines for which “CF” oils were specified. Older equipment and/or two-stroke diesel engines, especially those calling for monograde products, may however require “CF” category oil.
CE Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CD-II Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CD Obsolete CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CC Obsolete CAUTION: Not suitable for use in most diesel-powered engines built after 1990.
CB Obsolete CAUTION: Not suitable for use in most diesel-powered engines built after 1961.
CA Obsolete CAUTION: Not suitable for use in most diesel-powered engines built after 1959.

Diesel Engines

(Follow your vehicle manufacturer’s recommendations on oil performance levels)

Category Status Service
FA-4 Current API Service Category FA-4 describes certain XW-30 oils specifically formulated for use in select high-speed four-stroke cycle diesel engines designed to meet 2017 model year on-highway greenhouse gas (GHG) emission standards. These oils are formulated for use in on-highway applications with diesel fuel sulfur content up to 15 ppm (0.0015% by weight). Refer to individual engine manufacturer recommendations regarding compatibility with API FA-4 oils. These oils are blended to a high temperature high shear (HTHS) viscosity range of 2.9cP–3.2cP to assist in reducing GHG emissions. These oils are especially effective at sustaining emission control system durability where particulate filters and other advanced aftertreatment systems are used. API FA-4 oils are designed to provide enhanced protection against oil oxidation, viscosity loss due to shear, and oil aeration as well as protection against catalyst poisoning, particulate filter blocking, engine wear, piston deposits, degradation of low- and high-temperature properties, and soot-related viscosity increase. API FA-4 oils are not interchangeable or backward compatible with API CK-4, CJ-4, CI-4 with CI-4 PLUS, CI-4, and CH-4 oils. Refer to engine manufacturer recommendations to determine if API FA-4 oils are suitable for use. API FA-4 oils are not recommended for use with fuels having greater than 15 ppm sulfur. For fuels with sulfur content greater than 15 ppm, refer to engine manufacturer recommendations.
Image

Additives

Additive What It Does How It Works
Extreme Pressure (EP) Agents
  • Prevents welding and subsequent wear or seizure of contacting metal parts under extreme or shock load conditions.
  •  Additive combines chemically with surface to form a surface film.
  • Reaction usually occurs at high temperatures, which result when asperities collide.
Emulsifier
  • Promotes rapid mixing of oil and water promoting formation of a stable emulsion.
  •  Reduces interfacial tension and permits intimate mixing of oil and water.
Foam Inhibitor
  • Prevents formationof stable foam.
  •  Promotes combination of small bubbles into large bubbles, which in turn collapse more easily.
Friction Modifier
  • Alters coefficient of friction.
  •  Forms an easily sherable film on metal surfaces.
Metal Deactivator
  • Reduces the catalytic effect of metals on oxidation rate.
  •  Forms an inactive film on metal surfaces by combining with metallic ions.
Rust Inhibitor
  • Prevent rusting of ferrous (iron or steel) machine parts.
  •  Forms a film on ferrous parts thus protecting them frm water or other destructive materials.
Pour Point Depressant
  •  Lowers the pour point and enables the lubricant to flow at low temperature.
  •  Changes the size and shape wax crystals.
Viscosity Modifier (VM) or Viscosity Index Improver (VII)
  • Reduces rate of change of viscosity with temperature and makes possible the formulation of multigrade oils.
  •  Polymers uncoil as temperature rises, thus increasing their effective size and viscosity.
 Antiwear Agent
  • Minimizes wear caused by metal-to-metal contact during conditions of mild boundary lubrication.
  •  Additive reacts chemically and forms a film on metal surfaces under normal operating conditions.
 Antioxidant or Oxidation Inhibitor
  •  Inhibits varnish and sludge formation.
  • Reduces viscosity increase resulting from oil oxidation.
  • Reduces formation of corrosive acids.
  •  Slows the rate of reaction with oxygen by interruption of chain reactions or by decomposing reactive peroxides.
 Demulsifier
  •  Loosens and breaks stable emulsions.
  •  Lowers emulsion stability.
 Corrosion Inhibitor
  •  Prevents corrosive attack on nonferrous metallic surfaces.
  •  Forms a film on nonferrous metallic parts thus protecting them from attack by contaminants in the oil.
 Detergent
  •  Prevents oxidation products (gums) which have formed in the oil form sticking to metal parts.
  • Neutralizes acidic contaminants.
  •  Chemically react with oxidation products (gums) so that they remain soluble in the oil and do not stick to metal surfaces.
  • Metallic Base Reacts With Acid
 Dispersant
  •  Keeps oxidation products separated and suspended in the oil, retards formation of sludge and reduces soot related viscosity increase.
  •  Additive adsorbs on surface of gum particles or soot and inhibits agglomeration.