Not too long ago I stopped buying oil by the quart, and started buying it in big plastic jugs emblazoned:
"5 1/2 quarts, A complete oil change" or some such.
So I go to my friendly local parts store, and I see gallon jugs. The tag on the shelf still says 5.5 quart, $14.99. But the jugs clearly say 1 gallon. Oh, thinks I, what a bother. Now I have to buy a separate quart, too, which I did.
As I'm heading over to the register, I'm wondering what they're going to charge me for my gallon. You guessed it, $14.99. That's a 37.5% jump, in a time of virtually zero inflation, on a commodity whose price is stable if not falling.
Maybe I'll go to the 5k intervals after all.