How often do you purge yours? I have been doing it at oil changes about every 1.5-2 months. I am having some studdering issues like the fuel filter is clogged. I have a new filter on order at Napa for tomorrow morning but the counter jockey kept saying to drain the water seperater first. I have put 20K on this truck since I got it and never changed the box style filter so I am doing it anyway. Just curious how often you drain the water seperater and if you change your routine for different seasons? Different condensation in different weather?