It all depends on the car. Some cars will clog filters with one tank of biodiesel and others it will take a few tank full. Some kind of deal with the fuel lines. You may not see any breakdown of the lines for a year, or it make take a couple weeks. My 240 clogged filters with one tank of B50, while the wagon never really clogged up, altough I did change it's filters a few times.
With B5 or B20 you most likely aren't going to see a whole lot of fuel line breakdown. You may got through 2 or three filters though. I would have on hand 2 or 3 of each filter and have them in the car with out for a quick change on the road. Keep an eye on the fuel lines. Your fuel injector lines will probably go first.

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