Wet beats dry any day of the week even when dirty. That has been proven time and time again in countless industry studies and tests. If you are worried that much about dirt or sand getting in your gears simply cover them. My tanks are driven exclusively in the desert South West region of the U.S. and not once have I gotten any sand in the gear boxes and I run my tanks harder and faster than most.

Sure you are going to get the “axles” to hold dust and dirt when greased/oiled but getting dirt or sand in the gearbox is far less likely and even more so if you cover the gears with something as simple as a piece of paper. Running the axels with dry lube is one thing, but the gearbox? Neither Heng Long or Tamiya do or recommend that.