Over the summer my wife went to fill her car with midgrade (91) at the local brand new 7-11. It'd pump for maybe 3 seconds before it shut off. So she tried again. And again. Then went to a different pump at the same station. Same thing. So then she came home and told me her car was broken. I went to the same station, rang up a few $0.34 midgrade transactions myself, then tried straight 93. Didn't work at all. So I tried the 87, worked perfect. Went home, told my wife I fixed her car, haven't had to deal with it since.