We usually get diesel when the tank is down to a quarter or a third of a tank as it is easier than trying to find a place that pumps diesel when our range is down to 30-40 miles with our available fuel. Less than a fourth of the time are we putting in more than $100 and when we do my wife goes inside with the card and I put in the fuel. As things go it is a non issue for us.
When traveling we put all the fuel on one card which makes it easier to reconcile after a trip. We use a different card for other charges when we travel. When we get back home we have both credit cards reissued by the bank so we get new card numbers and the banks shut off the old numbers. We pay nothing to have this done and they will even overnight the cards to us at no charge if we ask them to do so.
When someone takes down your credit card information they will often wait a month or longer to start using the card so you do not connect the fraudulent charge to the last place you used the card. They also usually do a small transaction to see if the card is still good.
When we see a transaction and charge for a small amount we research it and if it is bogus we immediately call the bank and have the card killed. This past week we had this with a charge that was a little over $6, which some people might ignore, but we did not. It was the warning shot before the person started a buying spree.
Gas purchases are also a special animal as I learned after twice having my credit card flagged at a Macy's during the holidays. The second time it happened I asked the credit card agent why this was happening and I was told that my having purchased gas for my car and then followed that transaction with a large purchase at a department store raised a flag. Credit card thieves I was told will typically fill up there car/truck and then head to places where they can buy appliances and electronics that are easy to sell at flea markets and turn into cash.
When we travel out of state or out of the country we will call the credit card companies whose cards we will be using and tell them where will be going and for how long. This greatly minimizes problems with our cards.