How often should I change fuel filters?

I don't change mine unless they plug and I start to experience low power. Some of my diesels haven't seen a filter change in many years. You can put a new filter on an engine and have it plug with one bad tank of fuel. If you never get a bad tank of fuel you might never need to change the filter. My way of thinking says changing the fuel filter once per year makes as much sense as changing tires once a year. I could see changing it every 5000 gallons of fuel.