Next on the list of factors is pressure. When you increase the surrounding pressure, you can usually dissolve more gases in the liquid. Think about your soda can. It is able to keep the fizz inside, because the contents of the can are under higher pressure.
Assuming a prop, it depends on how you are propped but with a redline of 6000 rpm, most outboards perform best with a cruise in the 4000-4400 rpm range. If you want top fuel economy, get a floscan or such and see what is the most efficient for your engine and prop.
After flushing the outboard, allow the water to completely drain from the engine (see Step 2 before you shut off your engine if you plan to fog your engine manually). Your outboard should be in a vertical position for the water to completely drain.urn the garden hose 1/2 to full before starting your engine to get a good water flow without too much pressure (to minimize air bubbles). Run your outboard at normal idle speed for 5-10 minutes to allow the engine to warm up. It is best to use a mixture of stabilized fuel with fogging oil.