I've seen way too many stations with three underground storage tanks to believe that. That's one of those myths that's stuck around like the "010/020 high nickel blocks" and all of the other automotive myths. More people will tell you that, than will agree that they splash mix midgrade fuel at the pump when you pull the handle on midgrade fuel.Roundybout wrote: ↑Mon Jul 08, 2019 10:32 pm Another thing to consider is there's no separate tanks (usually) of the different octanes advertised at the station. It's a large tank of lower octane fuel and a smaller tank of higher octane. To get 89 mid grade it's blended right at the pump from the two tanks. Who knows how accurate that is between different stations. Some higher altitude regions have 85 octane as the base and it's blended up to the higher octanes at the pump. What the cheap stuff is composed of or the higher octane for that matter and how long it's been there is anyone's guess. You'll often see when a station is out of 87 they only have higher octane available and vice versa with no mid grades. AV gas at least has more stringent quality controls because it's bad to have a plane fall out of the sky due to poor quality fuel. The only thing it has going for it is the octane though and isn't formulated for passenger cars. The list of differences other than just octane can be substantial.
If that, were actually the case, why would they have 3 tanks at every station I've ever remembered looking at?
. (Yes, if you were really going to do that there would be lots of other expenses like travel, buying certified gasolines to verify the calibration, probably sending the unit in once a year to be recertified, etc.) Anyway, just wanted to pass on what I learned.