Brother HL-3450CN - Manual (Page 127)

CHAPTER 5 MAINTENANCE
5-11
Replacing the Oil Bottle
1. Press the Power button to turn off the printer and wait until it has cooled
down sufficiently.
2. Open the Top Cover.
3. Release the Oil Bottle Lock
Levers as shown:
Fig. 5-4
4. Remove the empty Oil Bottle from the Fusing Unit. Hold a sheet of paper
under the Oil Bottle and lift it out of the Fusing Unit. Move the bottle away
from the printer to the right so the oil will not spill into it. Be careful not to
spill oil inside the printer. It could cause considerable damage to the
printer.
Fig. 5-5