is eventually going to be a problem imho. I have seen it over and over through the years. The 10 micron final is plenty small enough, again imho, and is well within Yanmar's criteria. It will also be a lot more forgiving should things turn sour. I run a 30 micron preliminary racor and 10 micron final and change them once each season. I do run a biocide the in fuel and keep a close check on contamination in the sight glass of the racor. As an example, once in the Bahamas a group of five of us took on fuel in Freeport for a long run (all were motoring as we were beating dead into some pretty sporty conditions.) The fuel we took on initially looked a little murkey, but everyone agreed it should be fine (and there was no other option.) About four hours into our run three of the five boats fell out with engine problems and had to change filters in some very challenging conditions. Later in port all three had to change filters again. It was found that all three of the problem boats were running 2 micron finals. The two of us using 10 micron finals did not experience problems ...there might have been other mitigating factors of course ...just saying. I could site a good many like instances which have strengthened my resolve over the years in favor of the 10 micron final. Yet another down side to the 2 micron filters in the opinion of many mechanics, is that the constricted flow of the 2 micron filter stresses the standard engine driven fuel pump - by way of early diaphragm failure - this has been very well documented in the larger diesels in motor vehicles. The old Yanmar board had a very comprehensive discussion (by some involved Yanmar engineers) on this issue years ago. At that time, it was also agreed that the wear factor on an engine using 10 micron filters was pretty much indistinguishable from one using 2 micron finals.