Light dewaxed oil was produced through dewaxing process of the light waxy distillate raffinate of crude oil from Western Desert of Egypt using methyl ethyl ketone/toluene mixed solvent. Hydrofinishing process was used to remove the non-hydrocarbon constituents and to improve the physicochemical properties of the produced oils such as color, viscosity index, inhibition responses, oxidation and thermal stability. The operating parameters which affected the quality of the hydrofinished oils were

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... udied separately at different values that including reactor temperature, reactor pressure, liquid hourly space velocity and hydrogen to hydrocarbon ratio. The optimum operating conditions to be adopted for producing high quality automatic transmission fluid base oil were reactor temperature 290 o C, pressure 130kg cm 2 , liquid hourly space velocity 0.4 h 1 and hydrogen/hydrocarbon ratio 800 Nm 3 M 3 . The effect of changing hydrofinishing temperature and liquid hourly space velocity on the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions as well as their thermodynamic parameters were estimated. Calculations of activation energy (Ea) and free energy of activation (∆G) indicated that HDS was easier to occur than HDN and these reactions are more faster at higher temperatures. The effect of commercial and formulated additives on the quality of the hydrofinished oil was also studied. Automatic transmission fluid possessing the Dexron IID specification was produced by adding 7 wt% from Infenium T442 additive or by adding 9 wt% from Lubrizol ® 6701 D additive to the hydrofinished light dewaxed oil. Oils with the same efficiency were also produced using a formulated additive containing 4% viscosity index improver, 1.5% anti-oxidant and 1% anti-wear. The effect of increasing Infenium T442, Lubrizol R 6701 D and formulated additive percents on the protection efficiency of the automatic transmission fluid was studied through AC impedance technique. According to this technique, the effect of these additives on the corrosion rate of carbon steel coupons can be negligible.