As noted before, this is an incorrect line of thinking. I get it that YOUR drains are clear, but that, in no way, means other engines will be. One experience with one engine doesn't mean it's the same for the tens of thousands of others out there and promoting that can only lead to someone following misinformation and ending up with a huge repair bill. These lines can, and do, get clogged - I've seen it many, many times. I'm offering guidance based on many years of real life experience... and quite honestly, with a heck of a lot more boats than you are experienced with. I don't mean that in a negative way - just that facts are fact.