rear gear oil

i just recently install my moser 60 and they said not to run synthetic witch was what i was going to do till they told me not to :/ so question what gear oil are some of you guys running ? mine is danna 60 410 gear Detroit locker

If warranty comes in to play, which will be zero if you're racing it, I would get it in writeing from the outfit you bought the assembly from what the recommended oil and additives are.