Filled half the gas tank with the wrong octane...I should be okay, right?

[ChuckL]

So, I have the COBB 91-octane map on my car but I always fill it with 93 octane. I had around 2.5 gallons in the tank when I stopped at the gas station to fill her up. The gas tank is half full when I realize I'm putting in 87 octane, so I fill the other half with 93 octane. I'm guessing if I drive "normal" there's no reason to change the map back to stock, or economy, or anything like that....right?

 

[Rhinopolis]

So, I have the COBB 91-octane map on my car but I always fill it with 93 octane. I had around 2.5 gallons in the tank when I stopped at the gas station to fill her up. The gas tank is half full when I realize I'm putting in 87 octane, so I fill the other half with 93 octane. I'm guessing if I drive "normal" there's no reason to change the map back to stock, or economy, or anything like that....right?

The car holds 12.4 gallons, and 6.2 of 87 mixed with 6.2 of 93 should net you 90 octane. You should be fine and take it easy until it's 3/4 full then fill up with 93 and you will be at 91 octane.

 

[ChuckL]

The car holds 12.4 gallons, and 6.2 of 87 mixed with 6.2 of 93 should net you 90 octane. You should be fine and take it easy until it's 3/4 full then fill up with 93 and you will be at 91 octane.

Thanks!

 

[Rhinopolis]

PS: This fuel calculator is handy and is what I utilize to get correct ethanol percentages when I blend for E30 to E40 at the pump. I have the web address saved on to my iPhone under favorites.

Look at the calculator at the bottom of the web page, and focus on the octane using 10% ethanol which is what most gasoline manufacturers add in to their fuel. Do the correct gallons of whatever octane or ethanol fuel you are running and the program will calculate their combined result.

http://www.intercepteft.com/calc.html

 

[Chrisklol]

You will be fine even for aggressive driving. The ecu should detect any knock and retard the timing / boost if the octane becomes an issue.