RC gear oil overfill

[TomIre]

Had my RC in it's side to sharpen blades and while it was there I drained the old gear oil out. Then filled it back up. It is a Big Bee RC and the drain bolt hole is high and on the side of the gear housing.
Happened to come across the manual and it says "Caution do not overfill". 1) how do I know what correct fill is? I just filled it until it started dripping back out. And, 2) what could possibly happen if it is "overfilled"? I can't see anything bad happening i do tend to put my hand on the gear housing (yes, everything is off) to check for excess heat/friction from time to time and no issues.

 

[CincyFlyer]

Overfilling can cause pressure to build up in the case, and can blow out seals or actually split the case.

 

[oosik]

Unless the unit has a fill plug and a check plug or dip stick (to check for correct fill ) - with the unit siting in operating position on flat, level ground - - fill until the gear oil come back out the fill plug hole. Biggest problem with overfill could be build up of internal pressure and blow a seal.

Surprised the Op Manual does not tell how to check fill level and what is the correct fill level. Read it carefully again. Call service techs at dealership where unit was purchased.