RUST PREVENTIVE CHARACTERISTICS OF ENGINE OILS: ASTM D6557
EXPLANATION
This bench test method was designed as a replacement for Test Method ASTM D5844 which was designed to measure the ability of an engine oil to protect valve train components against rusting or corrosion under low temperature, short trip service, and was correlated with vehicles in that type of service prior to 1978. Correlation between these two test methods has been demonstrated for most, but not all, of the test oils evaluated. This test method covers a Ball Rust Test (BRT) procedure for evaluating the anti-rust ability of fluid lubricants. The procedure is particularly suitable for the evaluation of automotive engine oils under low-temperature, acidic service conditions. ASTM Test Monitoring Center occasionally publishes Information Letters to update this test method.
TEST SUMMARY
Multiple test tubes, each containing test oil and a specimen, are placed in a test tube rack, which is attached to a mechanical shaker. The shaker speed and temperature are controlled. Air and an acidic solution are continuously fed into each test tube over an 18 h period to prevent a corrosive environment. The specimens are then removed, rinsed, and analyzed by an optical imaging system designed to quantify the antirust capability of each test oil.
TEST PRECISION
Repeatability: 15.15 AGV
Reproducibility: 18.89 AGV
No bias is believed to exist. However, this aspect of the test method will be reevaluated after the test method has been in use by several laboratories over an appropriate period of time.
