fuel filter change frequency FASS 100 w oem filter intact

You could change at the same time if desired but the stock filter should last longer as the fuel is now being filtered before it gets to the stock filter. I change the Fass filters every 10,000 miles and the stock filter once a year.

Pretty much the same here when I had that setup on a 2012. I'd change the Fass spin on at the same time as an oil change, 10k miles, then go 30 - 50k on the under hood OEM filter, which was maybe only 6 months for me, give or take.

Fass lift pumps for their titanium series state 25k to 30k miles for both the water separator and the fuel filter to be changed. At that many miles I just replace them every 2 years at closer to 15k miles including the oem filter 100$ every 2 years don't hurt me any. And I also run the 3000xl series which I think added more miles to 40k miles