Quick question for y'all...couldn't find this explicitly addressed searching old threads...is there any drawback to pumping a small amount of 87-octane gas into a bone-stock AP2? I inadvertently put about 4 gallons in yesterday, stopped when I realized my error, and then topped it off with 7-8 gallons of 93 octane. Mathematically, it averages to 91, but is there anything that should concern me about the presence of the low-octane stuff? The thing seems to run fine, but I didn't push it at all today. Thanks!

 

no problem... ecu will retard timing if octane too low.. just dont rag on the car and youll be alright. if youre so concerned, add some octane booster...but i wouldnt worry about it if you finished with 93

 

If you calculate this out, you are basically running a tank of about 91 octane. That's what's recommended for the S anyway. I don't see a need to do anything different.

 

even if you are running anything less than 91, the ecm will retard the timing to avoid anything serious.

just don't do it too often

 

to ensure that the 93 is blended homogenously with the 87 go do a bunch of donuts at a local supermarket parking lot

 

^
That's overkill. The four gallons of 87 octane won't hurt your car. Gas is mixable, ECU does wonders, and you've corrected your "mistake" by pumping 93 octane.

 

You should be fine as others have stated, but if you are really anal than just don't pull any WOT runs until your next fill up.

 

All we have around here is 91 octane. You're fine. Enjoy the car and don't make the same mistake again.