Dynamic near-isothermal techniques have proven to be valuable in assessing the tendency of aviation fuels to form surface and bulk insolubles under conditions of thermal-oxidative stress. These methods are applied to the investigation of three representative jet fuels, POSF-2827, POSF-2980, and POSF-2934, and changes in these fuels caused by the introduction of four candidate additives. Neat and additized fuels are evaluated during flow through a tubular heat exchanger at 185 degrees C. The average surface-deposition rate as a function of stress duration and the quantity of both surface and bulk insolubles are determined during complete conversion of the dissolved oxygen. The additives, introduced individually, include a common antioxidant, a metal deactivator, a dispersant, and a combination detergent/dispersant. The impact of each additive is discussed. Dispersants are found to cause the greatest reduction in total quantity of bulk and surface deposits. Several criteria are considered for evaluating fuels and fuel/additive combinations.