Not flushing a raw water–cooled engine is irresponsible! Salt or brackish water can cause corrosion damage, and freshwater marine organisms can cause clogs. In either case, you may experience performance loss and, eventually, engine failure.
Alternatively, flush after each day of use. Make flushing part of your daily routine and avoid sudden reliability issue's associated with poor maintenance.
Happy safe boating and remember " Always Flush it " with marineengineflushers.com