This method is for determining the relative stability of distillate fuels such as home heating oils or diesel fuels under short-term, high temperature, aging conditions involving air exposure. It may also be used to evaluate the effectiveness of additives in inhibiting sediment formation and color degradation of distillate fuels under conditions of the test. The test does not correlate well with field storage or 3 month 43 degrees C (110 degrees F) dark storage.

The method, and modifications of it, have been used since 1942 (C & NW RR), and it has been known by a variety of titles including EMD-Diesel Fuel Stability Test, Union Pacific Diesel Blotter Test (U P-Blotter Test), Santa Fe Blotter Test, Nalco 300 degrees F Test and the DuPont F21-61 Test. Of the tests listed, the DuPont publication is probably the most commonly used.