ok i got my nitrage buggy on monday ,it had a sticky oiley substance on the metal frame. first thing that i thought was the center diff was leaking so i called tamiya america and they said it was a spray that they put on the motor to keep it from getting corrosion. well i looked that the diff.oil that i had 30,000 and it was the same stuff on the frame, well i just opened my center diff. and guess what? bone dry and none in it so hopefully i caught a big problem before it happened ,my manual says put 2/3 oil in it how full should i put in there full it up or half? and is there a seal i can put on it to seal it better?