The Navy's interest in predictive stability tests arises from the desire to broaden the supply of diesel fuels by permitting the use of cracked components in the fuel blends. The exclusion of cracked materials, plus other quality assurance provisions in the current Marine Diesel Fuel specification, has allowed the Navy to procure superior quality diesel fuels for fleet use and logistic storage. Stability and compatibility have not been problems and, except for occasional troubles which appeared to be attributable to contamination, these fuels have given satisfactory service in the fleet for several years. Since fuels for Navy use will be stored for periods up to three years, adequate storage stability, compatibility, and performance in engines must be assured before this change can be made. This paper covers the U. S. Naval Engineering Experiment Station experiences and evaluations of the wide variety of stability tests considered for this purpose and gives a brief summary of our future plans to arrive at a suitable specification-type test.