These TRF filters are not in any ‘schedule’ to replace as they flow so little TRF. The filter it self is actually a fuel filter – where it does filter hundreds of gallons of gas in a year so – yes, they do get replaced in that job. So what are you to do with the second stencil you got in the kit? You create your new favorite coffee mug! Truth be known, this was one of the early test stencils and is not ‘correct’ and I did a crappy job by pulling the stencil too early!