API Automotive Gear Lubricant Service Categories - Scardjam.com

API Automotive Gear Lubricant Service Categories
API classifies automotive gear lubricants in terms of performance required by a particular application.
As in the case of engine oils, these classifications do not define or reflect oil viscosity. To completely
specify a gear lubricant, both the API service designation and the SAE viscosity grade are required.
Axle and transmission lubricant viscosities are defined separately in SAE J306 as shown below.
Multi-grade lubricants are normally used and each viscosity grade has distinct criteria for low and
high-temperature performance.
SAE Gear Oil Viscosity Grade Requirements
Requirements
Kinematic viscosity,
cSt @ 100°C
Minimum
Maximum
SAE Viscosity Grade
70W 75W 80W 85W 90 140 250
4.1
-
4.1
-
7.0
-
11.0
-
13.5

This designation denotes lubricants intended for gears, particularly hypoid gears, in axles operating
under various combinations of high-speed, low-speed, high-torque, and shock-load conditions.
Lubricants qualified under U.S. Military Specification MIL-L-2105E (formerly MIL-L-2105D) satisfy the
requirements of the API GL-5 service designation. Performance test details are in ASTM Publication
STP-512A, "Laboratory Performance Tests for Automotive Gear Lubricants Intended for API GL-5
Service."
API GL-5 quality gear lubricants possess adequate extreme pressure characteristics for essentially all
automotive gear applications to prevent wear, pitting, scoring and ultimate gear failure, along with
protection against oxidation, thermal degradation, rust, copper corrosion, foaming and water
emulsification. API GL-5 oils are relatively equivalent to MIL-L-2105E gear lubricants (see below) and
are the most widely used automotive gear lubricants in North America for automobile, truck, bus and
heavy construction equipment applications.
Military MIL-PRF-2105-E
US Military Symbol GO-75 GO-80/90 GO-85/140
NATO Symbol 0-186 0-226 0-228
SAE Viscosity Grade 75W 80W-90 85W-140
Kinematic viscosity, cSt @ 100°C
Minimum
Maximum
Brookfield viscosity
Max temp, °C for 150,000 cPs -40 -26 -12
Channel Point, °C, max -45 -35 -20
Flash Point, °C, min 150 165 180
API Service Designation GL-5 GL-5 GL-5
4.1
-
MT-1
This designation denotes lubricants intended for non-synchronized manual transmissions in heavyduty
services. Lubricants meeting MT-1 contain thermal stability and extreme pressure additives.
Service Designations Not in Current Use
Due to changes in manufacturers' recommended practices and the unavailability of proper testing
hardware, the API Service Designations GL-2, GL-3 and GL-6 are no longer in current use.
GL-2
This designation denotes lubricants intended for automotive worm-gear axles operating under such
conditions of load, temperature, and sliding velocities those 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.
GL-3
This designation denotes lubricants intended for manual transmissions and spiral-bevel axles
operating under mild to moderate conditions of speed and load where service conditions require a
lubricant 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.
7.0
-
11.0
-

The manufacturer's specific lubricant quality recommendations should be followed.
GL-6
This designation 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.