Automotive Gear Oil Performance Testing

As lubricant formulations change to meet higher performance standards, Southwest Research Institute (SwRI) continues to provide testing and evaluation services to meet industry needs for current specifications and new test method development.

The Institute performs required bench and performance tests to qualify automotive gear lubricants under the military MIL-PRF-2105E specification and the ASTM D 5760 MT-1 specification. In addition, SwRI conducts tests in support of vehicle manufacturers and component suppliers specifications such as Mack Trucks Inc. and the Eaton Corporation. SwRI frequently performs custom programs, tailored to a client's individual needs.

L-33 Moisture Corrosion Test SwRI engineers use this procedure to determine how effectively a gear lubricant prevents rust and corrosion when subjected to lengthy storage. An axle assembly filled with 40 ounces (1,183 ml) of test oil and 1 ounce (29.6 ml) of distilled water is operated for four hours and then placed in storage at a controlled temperature. After seven days, the unit is disassembled and rated for rust.

MIL-PRF-2105E Field Tests The Institute tests gear oils for heavy- and light-duty service under this specification. To evaluate lubricant performance, SwRI operates three Class 8 trucks for 200,000 miles (320,000 km) for heavy-duty service tests or five light trucks or sedans for 100,000 miles (160,000 km) for light-duty service tests. Tgear oil samples are collected at 20,000-mile (32,000-km) intervals and analyzed for insolubles, viscosity change, additive and wear elements, total acid and base numbers, and water content. The data provide the clients with a detailed analysis of lubricant performance as the test progresses. Upon test completion, SwRI inspects gears and seals for distress, and then reports on lubricant degradation.

High-Temperature Cyclic Durability Test (ASTM D 5579) Mack Trucks Inc. originally developed this test, which has become an industry standard test to evaluate a gear or transmission oil's thermal stability and frictional properties. This test uses a Mack 18-speed transmission operating at a sump temperature of 121 degrees Celsius. The transmission is shifted every six seconds until synchronizer failure.

Specialized Services

SwRI conducts a variety of fleet and laboratory procedures for new product research and development. These services, including gear and gear oil evaluations, can be adapted for various research requirements.

Ford VT-20, Trailer Tow Axle Oil Evaluation: SwRI breaks in a passenger car equipped with a nine-inch ring gear and 3.25-ratio rear axle. After 1,000 miles (1,610 km), a trailer is attached to the car and towed at 70 mph (113 km/h) with a 400-pound (1,779N) pull at the hitch until the axle oil temperature stabilizes or the axle fails.

GM Big Wheel/Little Wheel Oil Evaluation: The Institute evaluates the special properties of limited-slip differential oils. Vehicles equipped with limited-slip differentials are operated with different size tires on each side of the drive axle. Axle noise, feel, and bias retention are periodically evaluated.

Truck Axle Oil Fuel Economy Evaluation: SwRI evaluates the fuel economy associated with axle oils in heavy-duty trucks using SAE and TMC procedures. Precision fuel consumption equipment measures precise speed, time, and distance controls during these road tests.

Evaluation of Gear Test Parts: Trained SwRI personnel rate test parts at the Institute or in the field. The Institute also offers training in gear surface distress evaluation.

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