After the measurement of the residual antioxidants of the oxidized oil samples, the oxidized oil samples were testing for their residual initial oxidation temperature (IOT, shown in Table 2). It is easy to find the residual IOT values decrease with decreasing residual antioxidants for their antioxidation ability gradually decreased. At the same time, the color number of the oxidized fully formulated aviation oil samples (Figure 2s) dramatically increased for the rapidly increasing color-related-oxidation-products shown in Table 1. As discussed above, most color-related-oxidation-products are generated from the reaction of antioxidants.

Table 3 The total acid number of the 928 and 50-1-4Ф aviation lubrication oil samples oxidized for 2 hours (mgKOH/g)