One question....when stating truck fill, I am assuming the 2,600 us gal tankers or bigger. WHy would you want to consider coins for this type of filling? Coins would be a hassle for the large filling.
I have used coin fills for 300 gallons or less, and the person must hold a button to ensure the flow continues...resulting in little spillage and waste.
I use a keycard system. It is terrific for billing and easy for the operator. Just my thoughts.
