Gas octanne in 3.6
07-09-2014, 01:59 PM
#32
Not even close to the point of the post, but since you mentioned it, here is how it IS related. Lead in the form of tetraethyllead was added to gasoline to increase octane until the 70's. Now other additives are used and we call it unleaded. Ethanol is one of these additives used to increase octane. One method is to add it in the form of MTBE, made by synthesizing ethanol and isobutylene. (But other methods are generally cheaper) When adding anhydrous ethanol (as in today's ubiquitous E10 gasoline), it raises the octane rating by a couple points. 
Facts, not marketing.
07-09-2014, 08:29 PM
#33
JK Enthusiast
Join Date: Jul 2012
Location: Lake City, FL
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Your mileage can/will literally vary. My last two cars, 2008 4.7 v8 4runner and 2012 Ridgeline both had higher milege with 91. Because I tow an enclosed trailer every other weekend to the track, I often used 91. Haven't tried with the jk yet because I want to form a strong baseline with 87 before starting my experiments. Only have a 1000 miles so far.
07-10-2014, 02:41 AM
#34
This makes perfect sense, if the computer will do that on a jeep. Anyone want to call and find out? 
I'm not sure about the other vehicles, but the 4Runner does so by design. In the manual it states that you will get better mileage and performance with the 91 octane but it will operate with as low as 85. If it senses that the fuel is lower octane, the computer adjusts the tune. In my experiences the milage was only a 1 or 2 mpg difference and the power was not noticeable.
07-11-2014, 05:43 AM
#36
JK Enthusiast
I realize that the Exxon/Mobile page I linked to does not contain any 'science'. It's simply a definition of what octane rating actually is, and a manufacturer stating that it, by itself, has nothing to do with energy contained or mileage. If my post made it seem like I was linking to a peer reviewed scientific article then I apologize for the confusion. I do not see any marketing material on that page however.
I just thought it would be helpful for the cool-aide drinkers to see that even the manufacturers of gasoline tell you that a higher than recommended octane rated fuel will not net any benefit.
I can see however that most people are still beholden to the 'feel it in the seat of my pants' logic rather than reality, so I will bow out of the conversation. Good luck to you all.
07-11-2014, 07:45 AM
#37
Octane?