ASTM D6121 Test Method for Evaluation of the Load Carrying Capacity of Lubricants
ASTM D6121 Standard Test Method for Evaluation of the Load Carrying Capacity of Lubricants Under Conditions of Low Speed and High Torque Used for Final Hypoid Drive Axles
4. Summary of Test Method
4.1 Prior to each test run, inspect the test unit (final axle assembly) and measure and record confirming manufacturing specifications.

4.2 Begin the test when the axle assembly is installed on the test stand and charged with test lubricant.

4.3 Gear Conditioning Phase - Run the charged test unit for 100 min at 440 wheel r/min and 394 lbf-ft (535 Nm) torque per wheel, maintaining an axle sump temperature of 297°F (147°C). (Warning - High-speed rotating equipment, electrical shock, high-temperature surfaces.)

4.4 Allow for axle assembly to cool and perform a gear inspection. (Warning - See 4.3.)

4.5 Gear Test Phase - Next, run the test unit for 24 h at 80 wheel r/min, 1742 lbf-ft. (2351 Nm) torque per wheel and an axle sump temperature of 275°F (135°C). (Warning - See 4.3.)

4.6 The test is completed at the end of the gear test phase. Visually inspect the test parts.
4.6.1 Remove the ring gear, pinion, and pinion bearing, and rate for various forms of distress. Use the condition of the ring gear and pinion to evaluate the performance of the test oil.

5. Significance and Use
5.1 This test method measures a lubricant's ability to protect final drive axles from abrasive wear, adhesive wear, plastic deformation, and surface fatigue when subjected to low-speed high-torque conditions. Lack of protection can lead to premature gear or bearing failure, or both.

5.2 This test method is used or referred to in the following documents:
5.2.1 American Petroleum Institute (API) Publication 1560 - Lubricant Service Designations for Automotive Manual Transmissions, Manual Transaxles, and Axles.

5.2.2 STP-512A "Laboratory Performance Tests for Automotive Gear Lubricants Intended for API GL-5 Service".

5.2.3 SAE J308-Information Report on Axle and Manual Transmission Lubricants.

5.2.4 Military Specification MIL-PRF-2105E.