The yellow silicone teat is designed for use with mayonnaise and oil based items.
How to disassemble the teat for cleaning:
Remove the complete teat assembly from the 1.5 gallon tank.
The part that is made of hard plastic and needs to be unscrewed into 2 sections. Holding the larger piece in one hand with the teat facing downward, grip the upper section and turn counter clockwise.
Remove the float inside. This looks like a stick with two weighted balls on each end.
To remove the teat out of the larger ring, hold in your hand and using your thumb simply apply enough pressure to the outside wall of the teat. This will break any seal the teak has with the ring and allow it to be removed.