Hello every body new guy here. I tried doing a search on this and either I don't know how to do a search or it hasn't been covered. but I have a 08 f250 diesel 4x4 with a 6speed, and have been searching what kind of fluid it takes, nobody can seem to give me a answer, I've been told to use every thing from 90wt gear oil to Motorcraft sp to standard 10w40, so I contacted ford and they said to only use XT-M5-QS 28 bucks a qt! There has to be something else I can safely use in its place. RP Synchromax? M1 manual tans fluid? Hows about this stuff. http://www.sypenl.com/wynn-synthetic-transfer-case-wynns-usa.html? Or is my only option the ford Fluid? Any info you could give me would a be life saver, thank you for your help guys.