How often to change the Fuel Filters is dependant on the quality of the Fuel you get from the Pump and your willingness and/or skill at changing a Filter on the Road Side.

We have all read stories on this Forum of someone on an out-of-Town trip filling up with some bad Fuel and having the performance effected or even rendered un-drivable.

I buy 98% of my Diesel Fuel from the same Station sinc 1992 and seldom drive more than 20 miles from home. I have never had a Filter plug up on me and effect my performance.

The longest I have driven with the same Fuel filter on my Volvo Diesel for as long as 5 years with no ill effects.
It has only 1 Fuel Filter; but the Filter does have a Drain on it and during the 5 years I drained in one time that I can remember.

But, previously I had changed it ounce a year or ounce every 2 years but not because it was plugged up; just preventative maint.
I do not carry extra Filters in either of my Diesel Cars.

So Fuel Quality and willingness to deal with a Road Side Filter change will be the "Tail Wagging the Dog" so-to-speak.

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84 300D, 82 Volvo 244Gl Diesel