To: heedm
It is not oil it is alcohol. The fluid is pumped under pressure and there is a fixed tube just behind the propeller. Mounted to the propeller is what is known as a slinger ring. The fluid is pumped into the slinger ring, which is spinning with the propeller. The fluid spins with the slinger ring due to some level of friction and in a sense becomes a part of the slinger ring. The slinger ring has small tubes that terminate several inches outboard of the hub and each blade has its’ own tube. Centrifugal force is the motivating force that pumps the fluid onto the backside of the blade.
So, the FAA answer to their question is “centrifugal force”.