I am on my second Z'ed (the first got nicked!) and I set my GPS for 220 miles and when I fill up I always zero the trip. I have on many occasions done at least more than my 'guessed' mileage before reserve, but I have NEVER put more than 18 litres in to refill the tank, even when I have gone into the reserve by maybe 20 miles. I do ride enthusastically and have the DNA filter and Kev mod.
What concerns me is that if I never use the reserve fuel, will it go 'off' over time?
.............or have I missed something?