API Service Classification  ("S" Service )

Service typical of older engines operated under such mild conditions that
the protection afforded by compounded oils is not required. This category
should not be used in any engine unless specifically recommended by
the equipment manufacturer.

Service typical of older gasoline engines operated under such mild conditions that only minimum protection afforded by compounding is desired. Oils designed for this service have been used since the 1930's and provide only antiscuff capability and resistance to oil oxidation and bearing corrosion. They should not be used in any engine unless specifically recommended by the equipment manufacturer.

Service typical of gasoline engines in 1964 through 1967 models of passenger cars and some trucks operating under engine manufacturers'
warranties in effect during those model years. Oils designed for this service provide control of high and low temperature deposits, wear, rust and corrosion in gasoline engines.

Service typical of gasoline engines in 1968 through 1970 models of passenger cars and some trucks operating under engine manufacturers' warranties in effect during those model years. Also may apply to certain 1971 and/or later models as specified (or recommended) in the owners' manuals. Oils designed for this service provide more protection against high and low temperature engine deposits, wear, rust and corrosion in gasoline engines than oils which are satisfactory for API Engine Service Category SC and may be used when API Engine Service Category SC is recommended.

Service typical of gasoline engines in passenger cars and some trucks
beginning with 1972 and certain 1971 models operating under engine
manufacturers' warranties. Oils designed for this service provide more
protection against oil oxidation, high temperature engine deposits, rust
and corrosion in gasoline engines than oils which are satisfactory for
API Engine Service Categories SD or SC and may be used when either
of these classifications is recommended.

Service typical of gasoline engines in passenger cars and some trucks
beginning with the 1980 model year operating under manufacturers'
recommended maintenance procedures. Oils developed for this service
provide increased oxidation stability and improved anti-wear performance
relative to oils which meet the minimum requirements for API Service
Category SE. The oils also provide protection against engine deposits,
rust and corrosion. Oils meeting API Service Classification SF may be
used where API Service Categories SE, SD or SC are recommended.

Oils meeting the performance requirements measured in the following
gasoline engine tests: The lID gasoline engine test has been correlated
with vehicles used in short-trip service prior to 1978, particularly with regard
to rusting. The IlID gasoline engine test has been correlated with vehicles
used in high temperature service prior to 1978, particularly with regard to
oil thickening and valve train wear. The V-D gasoline engine test has been
correlated with vehicles used in stop-and-go service prior to 1978, particularly with regard to varnish, sludge and valve train wear. The L-38 gasoline engine test requirement provides a measurement of copper-lead bearing weight loss under high-temperature operating conditions

Service typical of gasoline engine in passenger cars, vans and light
trucks beginning with the 1989 model year operating under manufacturers'
recommended maintenance procedures. Category SG quality oils include
the performance properties of API service category CC. (Certain manufacturers of gasoline engines require oils also meeting API Category CD). Oils developed for this service provide improved control of engine deposits, oil oxidation and engine wear relative to oils developed for previous categories. These oils also provide protection against rust and corrosion. Oils meeting API Service Category SG may be used where API Service Categories SF, SF/CC, SE or SE/CC are recommended.

Oils meeting the performance requirements measured in the following
gasoline and diesel engine tests

• The lID gasoline engine test has been correlated with vehicles used in short-trip service prior to 1978, particularly with regard to rusting-

• The IIIE gasoline engine test has been correlated with vehicles used
  in high-temperature service prior to 1988, particularly with regard to oil thickening and valve train wear

• The VE gasoline engine test has been correlated with vehicles used in stop-and-go service prior to 1988, particularly with regard to sludge and valve train wear.

• The L-38 gasoline engine test requirement provides a measurement
  of copper-Iead bearing weight loss and piston varnish under high
  temperature operating conditions.

• The 1-H2 diesel engine test requirement provides a measurement
  of high-temperature deposits.

Category SH covers the performance requirements of SG oils tested to the latest CMA protocol on engine testing. In addition, SH oils must meet various bench test requirements including volatility, filterability and foaming tests.

API Service Category SJ was adopted for use in describing engine oils
available in 1996. These oils are for use in service typical of gasoline engines in current and earlier passenger-car, sport utility vehicle, van, and light truck operations under vehicle manufacturers' recommended maintenance procedures.

Engine oils that meet API Service Category SJ designation may be used where API Service Category SH and earlier Categories have been recommended.

Engine oils that meet the API Service Category SJ designation have been tested in accordance with the CMA Code, may use the API Base Oil Interchangeability Guidelines and the API Guidelines for SAE Viscosity-
Grade Engine Testing.

Engine oils that meet these requirements may display API Service Category SJ in the upper portion of the API Service Symbol.
 

Engine oils that meet API Service Category SL designation may be used where API Service Category SJ and earlier Categories have been recommended.

Engine oils that meet the API Service Category SL designation have been tested in accordance with the ACC Code and may use the API Base
Oil Interchangeability Guidelines and the API Guidelines for SAE
Viscosity-Grade Engine Testing.

Starting July 1, 2001, engine oils that meet these requirements may display
API Service Category SL in the upper portion of the API Service Symbol.

Service typical of diesel engine operated in mild to moderate duty with high-
quality fuels and occasionally has included gasoline engines in mild service. Oils designed for this service provide protection from bearing corrosion and from ring belt deposits in some naturally aspirated diesel engines when using fuels of such quality that they impose no unusual requirements for wear and deposit protection. They were widely used in the late 1940's and 1950's but should not be used in any engine unless specifically recommended by the equipment manufacturer.

Service typical of diesel engines operated in mild to moderate duty, but with
Iower-quality fuels which necessitate more protection for wear and deposits.
Occasionally has included gasoline engines in mild service. Oils designed for this service provide necessary protection from bearing corrosion and from ring belt deposits in some naturally aspirated diesel engines with higher sulphur fuels. Oils designed for this service were introduced in 1949.

Service typical of many naturally aspirated diesel engines operated in moderate to severe-duty service and certain heavy-duty gasoline engines. Oils designed for this service provide protection from high temperature deposits end bearing corrosion and low temperature deposits in gasoline engines. These oils were introduced in 1961.

Service typical of certain naturally aspirated, turbocharged or supercharged
diesel engines where highly effective control of wear and deposits is vital,
or when using fuels of a wide quality range including high sulphur fuels. Oils
designed for this service were introduced in 1955 and provide protection from bearing corrosion and from high temperature deposits in these diesel engines.

Oil meeting the performance requirements measure in the following diesel and gasoline engine tests: The 1-G2 diesel engine test has been correlated with indirect injection engines used in heavy-duty operation, particularly with regard to piston and ring groove deposits. The L-38 gasoline engine test requirement provides a measurement of copper-lead bearing weight loss and piston varnish under high-temperature operating conditions.

Service typical of 2-stroke cycled engines requiring highly efficient control over wear and deposits. Oils designed for this service also meet the performance requirements of API service category CD.

Oils meeting the performance requirements measured in the following diesel and gasoline engine tests: The 1-G2 diesel engine test has been correlated with indirect injection engines used in heavy-duty operation, particularly with regard to piston and ring groove deposits. The 6V-53T diesel engine test has been correlated with vehicles equipped with two-stroke cycle diesel engines in high-speed operation prior to 1985, particularly with regard to ring and liner distress. The L.38 gasoline engine test requirement provides a measurement of copper-lead bearing weight loss and piston varnish under high-temperature operating conditions.

Service typical of many turbocharged or supercharged high performance diesel engines, operated under both low speed -high load and high speed -high load conditions. Oils designed for this service have been available since 1984 and provide improved control of oil consumption, oil thickening and piston assembly deposits and wear relative to the performance potential offered by oils designed for Category CD Service.

Oils meeting the performance requirements of the following diesel and gasoline engine tests: The 1-62 diesel engine test has been correlated with indirect injection engines used in heavy-duty service, particularly with regard to piston and ring groove deposits. The T-6, T-7 and NTC-400 are direct injection diesel engine tests. The T-6 has been correlated with vehicles equipped with engines used in high-speed operation prior to 1980, particularly with regard to deposits, oil consumption and wear. The T-7test has been correlated with vehicles equipped with engines used in lugging operation prior to 1984, particularly with regard to oil thickening. The NTC-400 diesel engine test has been correlated with vehicles equipped with engines in highway operation prior to 1983. particularly with regard to oil consumption, deposits and wear. The L-38 gasoline engine test requirement provides a measurement of copper-lead bearing weight loss under high-temperature operating conditions.

API Service Category CF denotes service typical of indirect injected diesel
engines, and other diesel engines which use a broad range of fuel types
including those using fuel with higher sulphur content, for example, over
0.5% wt. Effective control of piston deposits, wear and copper -containing
bearing corrosion is essential for these engines which may be naturally
aspirated, turbocharged or supercharged. Oils designated for this service
have been in existence since 1994. Oils designated for this service may
also be used when API service category GO is recommended.

API Service category GF-2 denotes service typical of two-stroke cycle
engines requiring highly effective control over cylinder and ring-face scuffing and deposits. Oils designated for this service have been in existence since 1994 and may also be used when API Service Category CO-Il is recommended. These oils do not necessarily meet the requirements of CF or CF-4 unless passing test requirements for these categories.

Oils meeting the performance requirements in the following diesel and gasoline engine tests

The T -6, T- 7, NTC 400 and L-38 engines: See API CE Category above for explanation.

The 1 K diesel engine test, which has been correlated with direct injection engines used in heavy-duty service prior to 1990, particularly with regard to piston and ring groove deposits. It has been demonstrated that the 1K test, in combination with test method 05968, the bench corrosion test, can be substituted for the NTC-400 test as an acceptable means to demonstrate performance against this category.

Test method D6483, the T-9 diesel engine test can be used as an alternate for the T-6 test and its limits.

Test method D5967, the F8A version, and its limits can be used as an alternate for the T-7 test and its limits.

API Service Category CG-4 describes oils for use in high speed four
stroke-cycle diesel engines used on both heavy-duty on-highway (less
than 0.05% wt. sulphur fuel) and off highway (less than 0.5% wt. sulphur
fuel) applications. CG-4 oils provide effective control over high temperature
piston deposits, wear, corrosion, foaming, oxidation stability and soot
accumulation. These oils are especially effective in engines designed to
meet 1994 exhaust emission standards and may also be used in engines
requiring API Service Categories CD, CE and CF-4. Oils designated for
this service have been in existence since 1994.

API Service Category CH-4 describes oils for use in high-speed, four-stroke diesel engines designed to meet 1998 exhaust emissions standards as well as for previous model years. CH-4 oils are specifically compounded for use with diesel fuels ranging in sulphur content up to 0.5 percent weight.
 
These oils are especially effective to sustain engine durability even under
adverse applications that may stress wear control, high temperature stability, and soot handling properties. In addition, optimum protection is provided against non-ferrous corrosion, oxidative and insoluble thickening, foaming, and viscosity loss due to shear. These oils also have the performance capability to afford a more flexible approad1 to oil drain intervals in accordance with the recommendations of the individual engine builders for their specific engines.
 
CH-4 oils are superior in performance to those meeting API CF-4 and API CG-4 and can effectively lubricate engines calling for those API Service Categories.

This material was prepared by the lubricants service Classification Task Force of the Fuels and lubricants Committee, Marketing Department, American Petroleum Institute, to assist manufacturers and user of automotive equipment in the selection of transmission and axle lubricants for the operating conditions as described.
 
In transmissions, and particularly in rear axles, gears of different designs are available for a variety of different service conditions. Selection of a lubricant for specific applications involves careful consideration of the operating conditions and the chemical and physical characteristics of the lubrican1 to meet these service conditions. Until recently, transmission and differential lubricants were described in qualitative terms and by a variety of designations, each one attempting to describe both the lubricant and the service conditions under which the lubricant must perform. Consideration of these lubricant designations to a minimum number was deemed highly desirable in the light of present day technology. The American Petroleum Institute, therefore, prepared six lubricant service designations for automotive manual transmissions and axles, each designation referring to the performance required of a gear lubricant for a specific type of automotive service. These designations also recognise the possibility that lubricant may be developed for more than one service classification and as a result may be so designated.

In developing the language for the service classifications, a need was recognised to supplement the descriptions for certain gear lubricants, particularly those for hypoid gears, by referring to a series of tests which would serve as a "test language" to provide more detailed information on the performance requirements of such lubricant This "test language" was developed by Section III of Technical Division B on Automotive lubricants of ASTM Committee D-2, and reference is made to these test procedures in the API service designations described below.

This system of designations replaced all previous API gear lubricant designations
and became effective May 1, 1969. These designations are as following

Designates the type of service characteristic of automotive spiral-bevel and worm-gear axles and some manually operated transmissions operating under such mild conditions of low unit pressures and sliding velocities, that straight mineral oil can be used satisfactorily. Oxidation and rust inhibitors, defoamers, and pour depressants may be utilised to improve the characteristics of lubricants for this service. Frictional modifiers and extreme pressure agents shall not be utilised.

Designates the type of service characteristic of automotive type worm-gear axies operating under such conditions of load temperature and sliding velocities, that lubricants satisfactory for API-GL-1 service will not suffice.

Designates the type of service characteristic of manual transmissions and spiral-bevel axies operating under moderately severe conditions of speed and load. These service conditions require a lubricant having load carrying capacities greater than those which will satisfy API-GL-1 service, but below the requirements of lubricants satisfying API-GL-4 service.

This classification is still used commercially 10 describe lubricants, but the equipment required for the anti-scoring test procedures 10 verify lubricant performance is no longer available.

Designates the type of service characteristic of gears, particularly hypoid⁽²⁾ in passenger cars and other automotive type of equipment operated under high-speed, Iow-torque, and low-speed, high-torque conditions.

Lubricants suitable for this service are those which provide anti-score protection equal to or better than that defined by CRC Reference Gear Oil RGO-105 and have been subjected 10 the test procedures and provide the performance levels described in ASTM STP-512A, dated March 1987⁽³⁾

Designates the type of service characteristic of gears, particularly hypoid in passenger cars and other automotive equipment operated under high-speed, shock-load; high-speed, low-torque; and low-speed, high-torque conditions. 
  
Lubricants suitable for this service are those which provide anti-score protection equal to or better than that defined by CRC Reference Gear Oil RGO-110 and have been subjected to the test procedures and provide the performance levels described in ASTM STP-512A dated March 1987⁽²⁾

This category is obsolete and is listed for historical reference only. The equipment used 10 measure performance is no longer available.

• Automatic or semi-automatic transmissions. fluid couplings, torque converters, and tractor hydraulic systems usually require special lubricants. For the proper lubricant to be used, consult the manufacturer or lubricant supplier.

• Automatic or semi-automatic transmissions. fluid couplings, torque converters, and tractor hydraulic systems usually require special lubricants. For the proper lubricant to be used, consult the manufacturer or lubricant supplier.

• Limited - Slip differentials generally have special lubricant requirements. The lubricant supplier shall be consulted regarding the suitability of their lubricant for such differentials. Information helpful in evaluating lubricants for this type of service may be found in the latest edition for API-GL-5 Service."

API GL-4 oils are not suitable for highly-loaded hypoid axies. API GL-4 oils are used in synchronised manual transmissions and transaxies as well as in mild hypoid and spiral bevel axies.