That's true to a point. But what has changed is the viscosity and make up of Biodiesel. It has random amounts of coagulants in it. It is a blend of vegetable, used cooking oil and diesel. They sometimes do not get the blend just right. The only way to get it to thin out is to keep it heated. A boat that is using biodiesel and keep running (with the return heating up the tank) sees almost no issues. But a boat with a tank full, and just sitting there will be crudded up in no time, and get filled with a 'gelatin' coating. Almost like wax or paraffin. The mentioned 'pre filter' of a centrifuge type filter is most often seen installed to combat this. BUT, the best way to avoid it is to not buy biodiesel.
What the manual says is often trumped with what is seen in the field. I frequently haul biodiesel in 4.2 million gallon lots. More often than not our tanks are a complete mess. The bio additive part is literally hanging off the frames and ladders in the tanks like strands of goo. The stuff is tenacious. It takes several hours of hot water washing to clean the tanks for the next load. Customers have to pay extra for cleaning to get rid of the stuff so it doesn't contaminate the next cargo. This was a huge issue several years ago when it was introduced, since no one knew about these qualities. The operators were left holding the financial bag since there had never been anything like this residue before, to deal with when switching cargoes. Now it is routinely put into the contracts that tanks with bio blends are subject to being professionally cleaned after haulage.
