cc - I have seen everything from water, to water with DOVE or Ivory dishwashing soap in it, (both are supposed to be not bad for the envirnoment), to peanut oil, and cooking oil. The last will gel and stop the entire system down. I don't recommend it.
I have seen several different types of set ups. Some nozzles spray onto the grass and some spray down the front of the hull to wet the polymer.
We have a vine down here we call pea vine that grows in the marsh over the grass. Has lots of sap in the leaves and forms a glue when you run over it. Without lots of speed or a spray you cannot cross it most of the time. Typically you don't see the plant until you are just on it and the sprayer will help cross it.
We get peanut oil from a friend working offshore, used in the frying vat, strain it through a screen and a cloth. It will not set up and stop the system down.
Big Daddy - having problems putting pictures up in the Gallery.
Most of sprayers have a Sur-Flo pumps with pressures from 30 to 60 psi and flow rates between 1 to 4.5 gallons a minute. Look up ag. sprayers at any of the outdoor equipment sites.