This is my set up . Fuel is only used for N.H. TC 30 . Last fill was 2 years ago , and actually was not a fill , just added 100 gallons to 60 or 70 that was still there . No minimum amount as long as they can wait till other customers in area need fuel also . Otherwise , they raise delivery charge to make it worth their travel . Holds 360 if filled , but most I have had in it has been 300 gallons .