4 Conclusions
According to the color investigation of the oxidized lubrication oil samples, we found that the color of the oxidized oil samples is mainly determined by the amount and species of antioxidants and oxidation conditions (including catalysts, temperature, time). Based on the incipient oxidation temperature, total acid number and tribological performances tests, the overall performances of the fully formulated aviation lubrication oil (T501 and Tz516 are used as antioxidants) would be remarkably reduced when the color number exceeds 23 at 250 oC oxidized for 2 hours. In the same case of fully formulated aviation lubrication oil with T531 used as antioxidants, the performances would decrease significantly when the color number exceeds 21 under same reaction conditions. The color number is proved that have potential practical applications in the field of fast determination of the quality and residual lifetime of the in-service aviation lubrication oil.