These are all really funny XD but i will try to be a bit serious.. I'm going to say this from some experience.
For the 15 bucks its worth.... buy a Madbull gear grease kit and pick up some red-tek from CT or an automotive parts store for the shafts and bearings.. for like another 6 or so.... maybe a shim kit :P
and do your gun right... When people ask how did you do it? charge 10 - 5 bucks a gear box.. to grease it plus parts (if they want to upgrade there box) and make your money back on the grease 2 times over in no time.
give your buddies a gun as good as yours..
EG, I know there is better out there but, currently I am getting 2100 rounds out of my gun off a single 8.4v 1200mah battery... with the stock motor and stock gears.
half of that was shot in full auto...
Madbull Gear Grease Here