ASTM D4425 – Oil Separation from Lubricating Greases by Centrifuging (Koppers Method)
Tests such as kinematic viscosity and biodegradability require an oil. If the oil of interest is in a formulated grease, the oil must be separated from the grease prior to testing. This test uses a high speed centrifuge to separate oil from grease so that the extracted oil may be tested.
The grease is placed into centrifuge tubes, and centrifuged in a high speed centrifuge until a sufficient quantity of oil is recovered.