unless you pull heavyor race your then almost any oil will work. My local stealership told me that the only reason for the Mopar oil is heat. I believe that Mobil one is just as good. I put normal 90w oil in mine (mistake if pulling)and when on my way from Texas to NC pulling heavy. I lost 5th gear when i topped a hill on I-59. I stopped in alatanaat a hotel that night and fixed it before I went to bed. All that happens is the 5th gear's nut will back off when the temp in the trans exceeds the max temp for the locktite holding the nut on. The gear will just slide back on the shaft but usually dont hurt any thing. Just run 4th and keep going. I put my back on with locktite and then beat the crap out the nut and threads (recomeended by the dealership) then refilled it with some synthetic oil from walmart and finished my trip to OBX NC. For the next 80k miles that I owned the truck pulling, I had no more problems. I dont believe in wasting money on Mopar oil.