I'm not against what you do. If it works for you, more power to you.
My point was a CC does the exact same thing as your DC does - except the money doesn't come directly out of your piggy bank. If there is a fraud charge on a CC, you are out $0 right off the bat.
Question about the debit card on gasoline - is that Arco by any chance?
I've done the mental gymnastics with that one. DC saves me 10 cents / gallon BUT they charge a one time 35 cent fee on the transaction. Is that the case for where you are?
In my case, save 10 cents a gallon on a 16 gallon tank means $1.60 in savings, minus the 35 cent fee for a DC, is 1.25 savings. But the CC gets 1.5% cash back, so assuming $5/gallon gas here and 16 gallons, that's $80 bill and a cash back of $1.20. In my particular case, the difference becomes negligible. And this math assumes I was nearly empty to fill 16 gallons to begin with. If I'm only partially filling, then the DC math falls apart - the 35 cent fee kills it. For that reason I end up using my CC for gasoline. Some CCs offer even more cashback for gas on rotating monthly/quarterly cycles. Mine doesn't.
I'm just going off on a tangent. More power to you, I have no issues with what method you choose, whatever works for you Sir