I bought an M38A1 a month or so ago. I need to drain all the fluids and start from scratch because I don't know the history on it. Some of my gaskets are leaking underneath so it'll be a good time to just change out those gaskets all at once. In the meantime, I've enjoyed driving it. I've been getting some puddles on the garage floor so I wanted to top off my trans/transfer case so I could continue driving it until I had a free weekend to change everything and replace those gaskets. I've ready all the threads about different lubs.

Main concern is, I don't want the trans/transfer lub to run dry while I'm driving it until I have time to change out the gaskets. I have noticed that it's not shifting as smooth lately and I know there isnt' a ton of oil in there to begin with.

Here is my questions, if I don't know what type of lube is in the trans/transfer case is it OK to top it off with something like the Royal Purple Max Gear Syn 75w90 oil to get by in the meantime? I feel like it currently has a gear oil and not regular motor oil in it, because the spots dripping on my garage floor have that sulfur smell of gear oil.