API Specifications

API CLASSIFICATIONS

API ENGINE OIL CLASSIFICATIONS

API stands for American Petroleum Institute. The API Service Classification System defines the performance level of a given oil, unrelated in the main, to oil viscosity.

The API requirements "S" for Spark Ignition (petrol) and "C" for Compression Ignition (diesel) can be briefly described as follows.

Petrol Engine Service Classifications

SA	Oil without additive
SB	Some antioxidant and anti scuff properties
SC	Meets 1964-1967 requirements of Automotive manufacturers
SD	Meets 1968-1971 requirements of Automotive manufacturers
SE	Meets 1972-1979 requirements of Automotive manufacturers
SF	Meets 1980-1988 requirements of Automotive manufacturers
SG	Meets 1989-1993 requirements of Automotive manufacturers
SH	Meets 1994-1997 requirements of Automotive manufacturers
SJ	Meets 1998-2000 requirements of Automotive manufacturers
SL	Meets 2001-2004 on requirements of Automotive manufacturers
SM	Meets 2004-2011 on requirements of automotive manufacturers. XW-20 and XW-30 grades have chemical limits
SN	Meets 2011-on requirements of automotive manufacturers. Limited to 0W-20, 5W20, 0W-30, 5W-30 and 10W-30 grades and have chemical limits
SA to SH	are obsolete.

Diesel Engine Service Classifications

CA	Light duty, high quality fuel, for MIL-L-2104A, 1954
CB	Moderate duty, lower quality (high sulphur) fuel
CC	Moderate to severe duty diesel and gasoline service MIL-L-2104B, 1964
CD	Severe duty diesel, including turbo, Caterpillar Series 3, MIL-L-2104C
CD-II API	CD plus Detroit Diesel 6V53T approval for two stroke engines
CE	Turbo/Supercharged heavy duty diesels from 1983
CF	Off road indirect injection diesel engines and others using a broad range of fuel types including high sulphur. May be used to replace API CD oils
CF-2	Severe duty two stroke diesel engine service from 1994
CF-4	Severe Duty four stroke diesel engine service for lower emission diesel engines (from 1988)
CG-4	Severe Duty four stroke engines meeting 1994 emission standards (less than 0.5 fuel sulphur)
CH-4	High speed four stroke engines meeting 1998 emission standards (less than 0.5% fuel sulphur).
CI-4	High speed four stroke engines fitted with cooled EGR (released Dec 2001) and using low-sulphur fuel.
CI-4 PLUS	As per CI-4 but with further restrictions on after shear viscosity and perform ance. (released September 2004). Aust. 2008.
CJ-4	Released in 2006 for 15ppm maximum fuel sulphur. Enhanced wear, protection 1.0% ash maximum. US EPA '07.
CA to CF-4	Are obsolete

API GEAR CLASSIFICATIONS

Introduction

The American Petroleum Institute listed service designations for automotive manual transmissions, transaxles, and axles. refer to the performance required of a gear lubricant for a specific type of automotive service. These designations also recognize the possibility that lubricants may be developed for more than one service classification.

Due to changes in manufacturers' recommended practices or due to the unavailability of testing hardware, the Service Designations API GL-2, GL-3, and GL-6 are not in current use.

Note: Automatic or semiautomatic transmission, fluid couplings, torque converters, and tractor hydraulic systems usually require special lubricants. Consult the manufacturer or lubricant supplier for the proper lubricant.

Service Designations in Current Use

API GL-1

The designation API GL-1 denotes lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers, and pour depressants may be added to improve the characteristics of these lubricants. Friction modifiers and extreme pressure additives shall not be used.

API GL-1 lubricants are generally not satisfactory for many passenger car manual transmissions. However, these lubricants have been used in some truck and tractor manual transmissions. Lubricants meeting service designation API MT-1 are an upgrade in performance over lubricants meeting API GL-1 and are preferred by major commercial vehicle manual transmission manufacturers. In all cases the transmission manufacturer's lubricant quality recommendations should be followed.

API GL-4

The designation API GL-4 denotes lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid (see note)gears operating under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications where MT-1 lubricants are unsuitable. The manufacturer's specific lubricant quality recommendations should be followed.

Although this service designation is still used commercially to describe lubricants, some test equipment used for performance verification is no longer available. Procedures to define this performance are currently being reviewed for adoption by ASTM.

Note: Frictional requirements for axles equipped with limited-slip differentials are normally defined by the axle manufacturer.

API GL-5

The designation API GL-5 denotes lubricants intended for gears, particularly hypoid (see note) gears, in axles operating under various combinations of high-speed/shock load and low-speed/high-torque conditions. Lubricants qualified under U.S. Military Specification MIL-L-2105D (formerly MIL-L-2105C) satisfy the requirements of the API GL-5 service designation, although the API designation does not require military approval. Performance test details are in ASTM Publication STP-512A.

Note: Frictional requirements for axles equipped with limited-slip differentials are normally defined by the axle manufacturer.

API MT-1

The designation API MT-1 denotes lubricants intended for nonsynchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting the requirements of API MT-1 service provide protection against the combination of thermal degradation, component wear, and oil-seal deterioration, which is not provided by lubricants in current use meeting only the requirements of API GL-1, 4, or 5.

API MT-1 does not address the performance requirements of synchronized transmissions and transaxles in passenger cars and heavy-duty applications.

API MT-1 lubricants should not be mixed with engine oils in the same transmission unit. Transmission manufacturers' specific lubricant quality recommendations should be followed.

Service Designations not in Current Use

API GL-2

The designation API GL-2 denotes lubricants intended for automotive worm-gear axles operating under such cond tions of load, temperature, and sliding velocities that lubricants satisfactory for API GL-1 service will not suffice.

Products suited for this type of service contain anti-wear or film-strength improvers specifically designed to protect worm gears.

API GL-3

The designation API GL-3 denotes lubricants intended for manual transmissions operating under moderate to severe conditions and spiral-bevel axles operating under mild to moderate conditions of speed and load. These service conditions require a lubricant having load-carrying capacities exceeding those satisfying API GL-1 service but below the requirements of lubricants satisfying API GL-4 service.

Gear lubricants designated for API GL-3 service are not intended for axles with hypoid gears. Some transmission and axle manufacturers specify API Category 'CC' or 'CD' motor oils for this service. The manufacturer's specific lubricant quality recommendations should be followed.

API GL-6

The designation API GL-6 denotes lubricants intended for gears designed with a very high pinion offset. Such designs typically require protection from gear scoring in excess of that provided by API GL-5 gear oils. A shift to more modest pinion offsets and the obsolescence of original API GL-6 test equipment and procedures have greatly reduced the commercial use of API GL-6 gear lubricants.