You didn't mention what size this Cessna is, but must be a doozy. If an 18-20 inch prop gives you any ground clearance problems, a 16-8 three blade will work well also, and not be "non-scale" for a 182. Like said above, everybody has a favorite oil and mix ratio, but I like either Klotz at 40:1 or Amsoil at 50:1 with standard 87 octane gas. I've got about two years' service out of my US-41 so far without a glitch or whimper (except for the spring starter), and it runs better and better. I have used as big as a 22-6 prop, but it was really too much, I have a 20-6 Dynathrust on it now and it hauls a 22 pound plane around real good.

Does yours have a spring starter? My spring broke after a year, but it seems to run better without it hanging on in back. It's not an easy engine to flip start, needs a lot of rpm for the mag to fire the plug, but an electric starter makes it a breeze.