EXPLANATION
This test method has been widely used to measure the oxidation stability of extreme pressure lubricating fluids, gear oils, and mineral oils. The changes in the lubricant resulting from this test method are not always associated with oxidation of the lubricant. Some changes may be due to thermal degradation. Many of the new extreme pressure oils cannot reasonably be evaluated by this test method.
TEST SUMMARY
The oil sample is heated to a temperature of 95° C in the presence of dry air for 312 h. The oil is then tested for precipitation number (by Test Method D91), and increased in kinematic viscosity (by Test Method D445).
TEST PRECISION
See the repeatability and reproducibility in Figs. 1 and 2.
This test method has no bias.