FTM-5307 Corrosiveness and Oxidation Stability of Hydraulic Oils, Aircraft Turbine Engine Lubricants, and Other Highly Refined Oils
This method uses small washer shaped metal specimens arranged vertically between glass spacers.
Metal test specimens may or may not be included and the number and type of metal specimens can also vary according to specifications. Briefly, the oil sample is placed in the test cell with the polished metal samples and heated in an oil bath or aluminum block for a specified time and temperature with dried or moist air (usually dried) bubbled through at a given flow rate. Acid number is sometimes monitored by periodic sampling.
Values reported at test end include sample mass loss, viscosity change, acid number change, mass loss of metal specimens, appearance of oil and test cell, and volume percent sludge. Oxidized oil and sludge samples are sometimes analyzed for metals content.