G520

I've toyed with the different octans from 91-87-85. Currently using 85 and have been for about 2500 miles. No knocks, pings, dings, or clanks. I didn't notice any MPG difference between the three different octans. That's the only reason why I keep using 85. No reason to use more expensive octans when I don't have to, IMO.

coltc2000

I gain 1 mpg with the 91, usually run 85 in my 08 and 09 JKs here in Utah

RckyMtnGoat

Good to hear, I am about 3/4 the way through my tank of 85 and haven't noticed any knocking or pinging yet but I have noticed a kind of studder right after take off almost like a miss in power doesn't happen when I am really on the gas only when I am easing up to speed. So far I am avg. about 18-18.5mpg which I have to say isn't bad for a combination between highway and city driving on stock 32's and 4.10 gears. More up dates to come but I have to run the whole tank and I may even have to do a multi tank to get a really good read. Thanks everyone for info.

Tonka_yellow

If I don't run 89 or higher I get check engine lights for O2 sensors. It says all 4 sensors are hot or something.

RckyMtnGoat

Crazy, I ran a tank of 91 through it already didn't have that happen at all though, that's kinda weird

RckyMtnGoat

Alright so towards the last 1/4 tank and the Jeep started knocking, not extremely loud but a knock non the less so I but some 91 in, don't think I will be running 85 in it due to the knocking, avg fuel mpg was around 18mpg and the only thing I noticed power wise was a slight sluggish feeling after a full stop. Now I have to burn this tank out and will try an 87.

hagausaf

I use the 85 grade at the shoppette on base and havent noticed any knocks but I'll listen closer now. Get around 14-14.5 mpgs currently which isnt too bad I dont think considering all the hills I have to commute over everyday.

RckyMtnGoat

Alright so recent stats on the fuel consumption.

Approximately 17.5mpg with Shell 87Octane

Approximately 16.6mpg with Costco 91Octane

Shell fuel actually felt like it performed better as far as compared to the 85 but I have yet to compare it with another 87. As far as 91 from Costco I would say they respond about the same or at least I can't tell a difference but as far as mpg it was a significant decrease. Now this is only with the on board gauge so its accuracy is debatable. I am getting ready to run the next four tanks with an OBD reader that monitors everything. I will post those results up as well but it may be a bit before I get those results up for you guys as it takes about 5-8weeks for that much fuel to be burned by me. Remember this is a Stock Rubicon 2012 Unlimited with no modifications except for an K&N air filter.

@hagausaf
The knock I was hearing was pretty hard to hear and I only heard it while it was warming up on one of the snowy mornings we had here a while back. I actually had to get under the vehicle to really hear it well so don't be surprised if you can't hear it. BTW glad that the pro cal work for you.

RckyMtnGoat

Alright Second Tank of Shell 87octane with mixed highway and city driving, approximately 1/4 of it being Highway and the rest is city. 357.2 miles with a fill up of 19.926 gallons for an approximate MPG of 17.93MPG. I figure do three tanks to get a good average then switch to the next brand. The ScanGuage Tool I am using was stating that I was getting something like 23MPG while on the Highway @ 65-75mph which made me just grin as I haven't had that kind of milage in years since i haven't owned a car lol. Alright so maybe I will do a fancy graph on here later comparing with a final write up.

RckyMtnGoat

Alright so I have some data to post and of course its always changing but at least I feel its good and reliable data. I just lifted the Jeep and she has some new shoes which is now going to change my average mileage which will be able to be seen in a couple of months. Note this is still stock gearing and as you can see the notes I know what I was doing or note anything that was out of the norm.

Awesome Chart and Graph!!!