similar story i have... when i first got my cai + tune i was low on gas already so i went and filled it up with the 92 tune and and when it was at like 40 miles to empty i went to the gas station and foolishly filled it up with 87 octane.. thankfully before i pulled off i caught my mistake and switched back to the 87 tune... no pinging ever nothing happened even though the 92 and 87 were mixed...

 

I have a 93 tune and done the samething. I just drove the car normally and everything was fine.

 

um, it's an extreme case compared to this one, but what about the thread last week where the kid's dad filled up his FI 93-tuned mustang with 87 and obliterated a piston and put a hole in one side of the block and a crack in the other side? Also I understand that even the best octane boosters only increase it by a fraction of a point. If you don't have an 87 tune I personally would NOT drive it, have the 87 drained out and put the correct octane back in. Paranoid maybe, but safe...

 

So, I have 2/3 of 87 and 1/3 of 91 in my gas tank.

I have reloaded the 87 tune on my computer.

Do need to take it easy on the car or can I drive it alike the usual madman that I am ?

 

You can drive normal now that you have loaded the 87 tune. You have a mixture now that is above 87 because of the 91 that you added, which is perfectly fine. Its ok to run higher octane gas than what youre tuned for, but NEVER run lower.