truggy diff fluid

I have a kyosho st-rr and Mike is making a chassis kit for me right now. I am going to use 2200 mmm combo on five cell maybe going to a 6 cell.

My question is what diff fluid would i use. I am thinking 15 20 5 front middle rear

I am mainly a basher. Keep that in mind. If i go to 6 cell I also dont want all the power spooling to the front wheels. What would you suggest for fluid. I also want to be able to wheelie.