I'm sure this has been talked and talked about, but I'd like opinions on fluid. Straight ATF? Petroleum or synthetic? Any luck with additives?

 

Either should be sufficient in the transfer case. The oil pump serves to keep everything lubed so as long as there is a lubrication characteristic of that fluid and a low viscosity, you are good to go. There are not any clutches that you need friction modifier for so that aspect of the fluid is mute.

 

straight cheap dyno mercron atf. doesnt need anything better.

 

Right on, thanks guys. How often do you guys change? I know how much you use the case has a lot to do with it, but every year seems cheap insurance?

 

Come to think of it I havent changed mine since I replaced the range shift fork 4K miles. I think checking it at least every oil change and adding as necessary would be the best route, changing when you change the transmission fluid would be best.