Gas Mileage and Octane and All That Jazz
08-09-2007, 05:18 AM
#1
JK Jedi Master
Thread Starter
Gas Mileage and Octane and All That Jazz
Just came back from our extended, annual camping trip. This year we visited San Diego, Yosemite National Park (NP), Redwoods NP, Lassen Volcanic NP, Crater Lake NP, Great Basin NP, Canyonlands NP and Moab. In case you're not familiar with all those places, that means we spent quite a bit of time at higher altitudes (relevant to the discussion of required octane).
Anyway, we diligently calculated our gas mileage after each fuel stop. I probably should have written it all down, but i didn't. However, we generally saw 20.+ mpg at most refuelings (with regular gas). The biggest exceptions were at the higher elevations where regular gas was 84-86 octane. Now, theoretically these lower octanes should work fine at higher elevations. But, we recorded as low as 14.5 mpg with considerable pinging after refueling with 85 octane in Moab. There was also a very noticeable loss of horsepower. So, at 1/2 tank, I refueled with 91 octane premium (at a different gas station, but still in Moab). There was virtually no noticeable difference in performance (pinging and horsepower), though the next refueling got us around 17.5 mpg. It wasn't until I'd refueled at about 1/4 tank with 89 octane that we noticed the horsepower return, though there was still some trace pinging (by this time we were in Albuquerque). After the next refueling, with 89 octane in Amarillo, the horsepower and performance were all back to normal, and our final refueling showed that we'd obtained 20.+ mpg again.
Pertinent fact to confuse the issue: There was some wheeling in there--we descended into Canyonland NP in 4WD-low, and spent about 1/4 of the mileage on backroads. Undoubtedly that caused some of the drop to 14.5 mpg. But, we've wheeled before and not had out gas mileage so heavily impacted. And that doesn't explain the significant decrease in horsepower and the annoying presence of pinging.
My thoughts: We got a bad tank of gas in Moab. Maybe more than one. It was really bad, enough so that two following refills, by supposedly higher octane gases than required for the JK at sea level, much less at higher elevations (typically 5K feet) weren't able to flush it out of the system. In fact, I wonder if bad gas isn't just something that's prevalent in the Moab area.
Anyway, what are your thoughts and experiences?
Anyway, we diligently calculated our gas mileage after each fuel stop. I probably should have written it all down, but i didn't. However, we generally saw 20.+ mpg at most refuelings (with regular gas). The biggest exceptions were at the higher elevations where regular gas was 84-86 octane. Now, theoretically these lower octanes should work fine at higher elevations. But, we recorded as low as 14.5 mpg with considerable pinging after refueling with 85 octane in Moab. There was also a very noticeable loss of horsepower. So, at 1/2 tank, I refueled with 91 octane premium (at a different gas station, but still in Moab). There was virtually no noticeable difference in performance (pinging and horsepower), though the next refueling got us around 17.5 mpg. It wasn't until I'd refueled at about 1/4 tank with 89 octane that we noticed the horsepower return, though there was still some trace pinging (by this time we were in Albuquerque). After the next refueling, with 89 octane in Amarillo, the horsepower and performance were all back to normal, and our final refueling showed that we'd obtained 20.+ mpg again.
Pertinent fact to confuse the issue: There was some wheeling in there--we descended into Canyonland NP in 4WD-low, and spent about 1/4 of the mileage on backroads. Undoubtedly that caused some of the drop to 14.5 mpg. But, we've wheeled before and not had out gas mileage so heavily impacted. And that doesn't explain the significant decrease in horsepower and the annoying presence of pinging.
My thoughts: We got a bad tank of gas in Moab. Maybe more than one. It was really bad, enough so that two following refills, by supposedly higher octane gases than required for the JK at sea level, much less at higher elevations (typically 5K feet) weren't able to flush it out of the system. In fact, I wonder if bad gas isn't just something that's prevalent in the Moab area.
Anyway, what are your thoughts and experiences?
08-09-2007, 05:58 AM
#2
JK Junkie
Join Date: Mar 2007
Location: Kennesaw, GA
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bad gas probably... i have it sometimes too...
and no... you can get bad gas anywhere... not just the moab!
j/k...
i havent had any bad experiences with fueling up.... however, i try to go to the stations that "appear" to be newer. I trust their tanks better. If i absolutely have to fuel up... then i will put just enough gas from a crappy looking station to get me to a good station.
never put anything except reg. unlead. in mine. i think its 87 here in GA... maybe 85... i dont know.. its the nozzle on the far left.
and no... you can get bad gas anywhere... not just the moab!
j/k...
i havent had any bad experiences with fueling up.... however, i try to go to the stations that "appear" to be newer. I trust their tanks better. If i absolutely have to fuel up... then i will put just enough gas from a crappy looking station to get me to a good station.
never put anything except reg. unlead. in mine. i think its 87 here in GA... maybe 85... i dont know.. its the nozzle on the far left.