Ok here goes...you have to keep in mind its all about the maps the ECU will look up. The car is rated at 412hp with 91 octane, 420 now for the 2013s. The issue is the timing map the car will run depending on the conditions. So to say that 93 octane will give better performance is probably a pretty sure thing providing all the other variables are there for the ECU to take advantage of this. I know this is kind of a half answer but it is what it is.

Even with 93 octane though the car may not see maximum timing tables, it may require even higher octane. The question is where is the diminishing return at. For the S65 powerplant in the M3 its 95 octane, anything above this and you are wasting your money. I think its safe to bet that the ECU in the Coyote powerplant is somewhat similar. If you are at sea level with cool ambient air and temps and you are running 93 octane,the other variables are in place, you will get to a higher timing table for the ECU as the chance of detonation with these positive variables will allow the higher timing table. The engine tries to adjust to the best timing table before knock occurs.

Keep in mind in hot weather you won't be able to use the high end timing table as the ambient air temp, along with other variables just won't support this table as detonation will be detected and the knock sensors will make the ECU pull back timing. Running higher octane in this condition can alleviate this somewhat.

Also, where in the country are you located. Are you usinig a Cali blend of fuel? Here in Cali our 91 is not the same as other 91s around the country. We can't even get 93 octane here. I have to blend 4 gallons of Sunoco GT 100+ to get me just over 93 octane, and yes there is a difference. It was worth 10rwhp for my M3 to go to 93 octane vs. 91.

Dave

 

If you can't tell the difference in horsepower between the two fuels, why spend the extra $ on the 93/94? You're not driving a NASCAR circuit, you're driving to work.

 

 

straight Kerosene

 

use jet fuel

 

Ok, sorry, I've been away from my computer all day and I'm just now reading all of the answers. By far this is the best one in my opinion, assuming the facts are correct. I must be honest and say that I'm not knowledgeable enough to be able to confirm this. I live in Northern Virginia, near DC, and I'm pretty much at sea level. We do have about 4 months here where it can get really hot, in the 90's and sometimes over 100, but most during the Spring and Fall it's generally between 60 - 80 during the days, and 30 - 50 at night. A normal Winter has temps in the 40's during the day, and in the 20's at night. It sounds like to keep this simple I should just use 91 octane with a stock tune. If I change the ECU map I will go with the recommended octane for that map. Thank you for answering my question, and saving me a little cash.

 

Here in CR there are only two options:

Super (95 octane)
Plus91 (91 octane)

I have never used anything but Super, but I only had european cars which ask for 95 or higher

 

Jet Fuel = Diesel

I used to put Jet Fuel on a Land Rover Discovery TDi we had, exhaust smelled great, LOL

 

I've had my 2012 for 6 months and I've literally only used Shell V-Power 93 octane so far. No knocking and it's supposedly pretty good as far as pump gas goes.

 

According to the other posts here, you should drop down to 91 if the have it because there is no benefit to anything above that. I know some Sunocco stations near me have 91, but I don't know if you have those.

 

Hmmmmm. I get jumped and attacked for using 5w-30 on an oil change; the manual states 5w-20. Now, the manual recommends 87 octane, but the usual rat pack are not jumping on this and stating to stick with the recommendations?

If a tune requires it, then I'd go with that recomendation; if no tune (factory settings), then it just has to be the factory recommendation. We're not supposed to question the design/development engineers.....

 

No... I clearly stated that there is a benefit to be had from premium but it's more in the lines of a detergent package as opposed to the extra octane.

 

Let it go dude...

 

Use diesel

 

Right. We don't need a third thread.

EDIT: For the record and to stay on topic, I run 93 only with a tune. If 95 was available around here, I'd run that.

 

I have used 93 since day 1. I even had my dealer fill it will 93 when I picked it up.

 

Here in MI we only have 87, 89, and 93/94 at most stations. It's had 93 its whole life.

 

Nope. Not recommended.

 

Neither was 5W-30.

 

I prefer 83 octane because I get less tickets.