maybe it was all in my head but here it goes...the other night i was on my way home and the stang wasat 10 miles to empty so had to stop for gas. it was about 1:30am so didnt have much selection as far as gas stations go. anyways, the station i stopped at was out of 93 octane so i had to put midgrade in (only $7.00 worth cause i was worried with my 93 octane tune)...15 mile drive home and parked her safely...the next morning, my car seemed to be more responsive and felt quicker than when i use the 93 octane.

has anybody else had this kind of experience???

since then, i have filled her up all the way with 93 octane and she seems to be running back to normal...how damaging could it be to put a tank of mid-grade gas in her next time to see if i am right or if it was all in my head???

 

I can say I have had some tanks of gas that worked better than others. I always run 93 octane. My problem is filling up and getting that tank ful that doesn't have enough octane. If mine worked better off of the 89 than I would run it unless it starting pinging. Sometimes I think there isn't much difference in the gas.

 

Actually if I am not wrong octane is just a measure of the fuel resistance to detonation or knocking but has no effect on performance.
Race engines usually require high octane fuel because they run high compression ratio and/or high boost.
It is not advisable to run almost empty because the fuel pumps in our cars are submerged and the fuel helps keep the pump at lower temperatures thus making it last longer, additionally if you drive on twisty roads while almost empty it can lead to lean fuel mixtures that are no good for your engine....humm sorry I think this is not what you asked, anyway for what is worth every time I wash my car I feel it faster, and quiter (interior noise)

 

For the final time... Unless you have your car tuned for higher octane gas, it does NOTHING for your performance! The only thing higher octane does is prevent predetonation, which is critical in advanced timing or forced induction applications. If you have a stock tune, you are wasting your money and imagining things. Now just stop it already! sheesh.

And for the starter of the thread, who appears to have a higher octane tune, your tune might not be as aggressive as it could be, and/or the cooler weather has minimized the effect of the reduced octane, and/or the gas station actually filled the lower octane storage tank with higher octane fuel for inventory control purposes. In any case, the lower octane fuel will burn more easily, and as long as it doesn't predetonate, it's all good.

 

Our cars have knock sensors, so even if you get bad gas (or have to temporarily run lower octane on a performance tune), the computer should keep you out of trouble.