While Teflon tape will work, over time oil / fuel will break it down. Bits and pieces can start floating in the fluid and maybe clog a filter screen.
Not so applicable for the Roxor manual transmission. But think about fuel lines and automatic transmissions.
Permatex 80019 Aviation Sealant is a nice product. It is a liquid you can apply to threads (on fuel lines, fill / drain plugs) or gaskets. Inside the lid is a fine brush. 4oz will last a lifetime and cost about $10.