Slimmy,
The use of fogging oil is an old habit carried over from God only knows  when 
and nobody knows why. What is going to rust? The exterior of the motor is  
painted, the carburetor is brass or some other cast material that won't rust.  
You can't get inside the float area without disassembly, so what good does  
fogging the motor do other than make it smoke when you fire it up in the spring?  
Putting fogging oil into the carburetor is sure to gum up the jets and  
orifices.
If your motor has a thermostat, the only way to get all the water out of  the 
system is to remove it and pour some nontoxic antifreeze into the cooling  
jacket. A motor without a thermostat will, by design, drain all water, including 
 from the water pump.
 
 
Rummy