Petro Dog is right in saying that less ethanol in gasoline will provide better fuel economy. Here's a web site for all to read. It provides lots of info on gas and alcohol.
http://www.hho4free.com/gasoline_vs_ethanol.htm

 

What people fail to realize is that 87octane is very DIRTY. After a while, carbon starts building up which in turn reduces performance.
Premium octane fuel burns cleaner and they actually have cleaners mixed in with the fuel where as lower octane does not.

Over time, you can clearly see which engine has run on 87oct vs higher 93oct fuel.


BTW, the piston skirts on the hemi's are very thin and it doesnt take a whole lot of pre-det to crack/break off a chunk. pre-det also puts very small gouges in the top of the piston and these create hotpots. They also cause turbulence and gather carbon buildup.

 

If 87 is dirtier, then the vast majority of cars in the US are in trouble. Here is what the Federal Gov has to say about that.

https://www.consumer.ftc.gov/article...ctane-gasoline
Will higher octane gasoline clean your engine better?

No, as a rule, high octane gasoline doesn’t outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

I was curious about this 87 is dirtier claim, so I googled "is 87 octane cleaner" and was surprised by the number of folks that claim the opposite, mostly in the majority.

One thing that makes a difference is the brand of gas you buy. There is this "top tier" gas that has added cleaning agents to it, it is however, added to all octane ratings, not just to 89 and up. Here is the list of the "top tier" gasoline brands.

http://www.toptiergas.com/retailers.html

TOP TIER Detergent Gasoline Retailers
Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.
In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.
Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.

• 76 Stations
• Aloha Petroleum
• Chevron
• Conoco
• CountryMark
• Entec Stations
• Exxon
• Hawaii Fueling Network (HFN)
• Holiday Stationstores Inc.
• Kwik Trip/Kwik Star
• MFA Oil
• Mileage Stations
• Mobil
• Ohana Fuels
• Phillips 66
• Quik Trip
• Rebel Oil
• Road Ranger
• Severson Oil
• Shell
• Texaco
• Tri-Par Oil
• U.S. Oil

 

Thank you Glenn

 

Everybody knows that, but did you know that the pyramids were actually a mistake?

 

Good point. Several years ago when I was driving the '03 hemi I didn't notice any difference in mileage between 87 and 89.

I guess the bottom line in all of this is that we really don't have much control into what we put in our tanks. We think we do. But we have no idea if the 89 we are paying extra for really has more octane and less ethanol. Where I live there is very little choice in what refinery the fuel came from (only 2 possible sources). Complicating this further is the deals that we don't know about such as refinery A supplying a gas station that usually uses refinery B to get them out of a jam. The trucks carrying the fuel are generic looking and some people have noticed the same truck at multiple brand gas stations on the same delivery run. I have even spoken to folks who have worked for local oil companies and they chuckle when asked about the different grades of fuel - what different grades?! It all comes from the same tank! But that is a different topic altogether LOL!

Cheers everybody!

 

Since ethanol raises octane, it seems unlikely that the higher octane fuels would contain less of it.

 

This is exactly why you are seeing a little better mileage on 89, and as Pedro has said the octane has nothing to do with the increased mileage, but the less ethanol surely will

 

That gas may have all come from the same truck, but according to my brother-in-law who delivers gas for Marathon, those trucks have different tanks within that large tank, and yes they do carry different octanes in each section of those main tanks, and also diesel so Glenn you weren't given very good information. As far as the same truck servicing various stations, I'm sure that happens. So from what I can get from picking his brain on this subject, different oil companies do share fuel on occasions. Most of the combined deliveries are to smaller gas stations that aren't affiliated to major oil companies, but the lesser known brands.

 

I have to disagree with your statement.
First off, Premium fuel has extra cleaners in it. So, not only does it burn better, consistent and cleaner than 87 octane which is very dirty I might add, it has additional cleaners that are added by manufacturer so it runs MUCH cleaner than 87oct.
Now, if you trade your vehicle in every 36kmi then no worries and you probably wont notice much if any difference at all. It's when the engine gets up over 50k you will certainly start to notice!
So, for the simple fact that Premium fuels are in fact premium, it's not wasting money. Your just keeping your fuel system and heads much cleaner which is actually preventative maintenance.
2nd. Since it burns cleaner, your MPG's can actually improve. I doubt it's noticeable enough to make it worth the extra expense if thats the only reason for using premium, but it will improve mileage because it burns cleaner and will not cause detonation which is basically your engine working harder to go the same distance. Cleaner engine ports flow better and will yield more power than chambers full of carbon and gunk.
Next, the Hemi is recommended to have 89oct because of the very shallow ringlands that are used for the pistons. They mimic'd NASCAR style because they are very high up on the piston. They are very thin. Excessive detonation can break this area apart and obviously cause some major damage. In fact it has on the older model Hemi's 03-08's with higher mileage. I'm pretty sure your 2014 uses the same style pistons as the older one's. I realize they say 87 is acceptable but it's definitely not preferred.

Lastly, you must drive regularly or I would stay away from 87oct. Especially if you have 10% ethanol blend like we do here in NYS. Ethanol degrades gasoline much quicker. In 3 weeks time, that 87 octane will become something like 84oct. It's crazy how fast gasoline will degrade with the ethanol mixed in. I know sealed tanks will increase the lifespan, but I choose 93Oct for my 91oct tune. My truck sits a lot. Matter of fact, my truck was parked in October and didn't move until April.