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I drive about 300 miles per week, mostly rural coastal Texas roads at 60-70mph with some city driving. My 08 RTL has about 130K miles. I use lowest octane for normal driving and 91 when pulling our travel trailer. I have consistently gotten high 16s low 17s mpg in normal driving. We were planning on taking the trailer out so I filled up with 91 oct but ended up driving the tank out before picking up the trailer and got 19+ mpg. I started using 91 oct all the time for the last several months and am getting ~2 mpg increase over my previous mpg every tank. Has this happened to anyone else?

Kelly
'08 RTL
Gibson exhaust. cold air intake, 30mm shorter springs
 

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Yep. I've never run 91 but I know I get better mileage on 93. I did the math and compared the increased mpgs to the increased cost. Pretty much comes out even. So I run the recommended 89 and call it a day. (unless I'm towing)
 

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Using the standard RON octane rating system the "recommended" octane is 87 not 89.
Then I stand corrected. But my truck gets TERRIBLE gas mileage on 87.
 

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I only use 91+ octane Shell Ethanol free gas and get better Gas Mileage with it. Owners manual recommends regular 87 unless you're towing. However, Gary Flint who designed the Ridgeline recommends 89+. I trust Flint's recommendation over the manual.
 

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I also run 89, but weird thing recently I went from getting 200 miles from a full tank to 240. Did the spark plugs just kick in like 2 months ago from changing them a year ago?
 

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This all sounds about right. I get about 8% better in combined driving with 89 versus 87. That pretty much exactly matches the difference in cost.
 

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I have to run 91 Octane at these temps (-40C and worse). I HAVE to. Its 8 MPGs on 87 vs 13MPGs in a stop and go environment.
 

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Wish this thing had an option to delete posts instead of just editing them. Put this response in the wrong thread. Doh!
 

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I only use 91+ octane Shell Ethanol free gas and get better Gas Mileage with it. Owners manual recommends regular 87 unless you're towing. However, Gary Flint who designed the Ridgeline recommends 89+. I trust Flint's recommendation over the manual.
Where does he recommend using 89 for non towing driving??
 

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2008 Ridgeline RTS in Billet Silver Metallic
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I ran an extended test using nothing but 87 octane nonE gas a while back and figured I got about 1.5 mpg improvement. Then they jacked up the price of the nonE gas to the point where it was no longer justifiable to use from an economic perspective.

I've lately been running 93 octane and estimate about 0.5 to 1 mpg improvement (I didn't expect any). But it's still Egas, and costs about 20 to 24 cents more per gallon than 87 octane Egas. And is still cheaper than 87 octane nonE gas.

I can't understand the government push for higher and higher CAFE standards and yet they still insist on imposing Egas on us.
 

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I can't understand the government push for higher and higher CAFE standards and yet they still insist on imposing Egas on us.
Over reaching gov't regulation on EVERYTHING. Don't even get me started.

On another note, I might be outfitting my RL with a turret.
 

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One note................... in many markets 91 octane contains no alcohol.
I haven't seen that in my area.

Puregas.org lists 5 stations in my area with nonE gas:


I checked the station at Oakview yesterday and their 87 non-Egas was 50 cents higher per gallon than the Egas. And their premium (93?) octane Egas was only 2 cents per gallon higher than the 87 octane non-Egas. (3.19/3.69/3.71)
 

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I'm 48 now and when I was a teenager my father used to work at a large oil refinery near Toledo...aka Hell. He spent a lot of time in the labs checking the various products that was refined there. Back then, some gas stations were still selling the economy 86 octane. It was so bad, the govt said no more, it creates too much pollution. He told me that the 87 wasn't much better and contains a lot more impurities. Going up to 89 was a different story. From 89 on up the gas is MUCH better. Its only 10 cents per gallon more BUT you get a lot of benefits from it. Better gas mileage, less carbon buildup on valves and cylinders, saves the O2 sensor, gives longer life to the catalytic converter and others. He said all cars should run on 89 or higher. Granted some car's computers get pissed off if you run higher than 87 and that's a shame. 89 or better is all I have ever run. I have had over 30 cars and they have all been very clean burning with no exhaust issues. You can drink tap water or filtered water. The more pure the better for you. The engine is no different. Better gas will lead to a longer life motor.
 

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Yep. I've never run 91 but I know I get better mileage on 93. I did the math and compared the increased mpgs to the increased cost. Pretty much comes out even. So I run the recommended 89 and call it a day. (unless I'm towing)
In my truck on the highway there is a bigger difference between 93 and 89 then there is between 87 and 89. I did the math also and around town although the mileage difference wasn't as big it was still worth buying the good stuff. Hands down and without question my truck downshifts less with the 93. Joe said there is around a 10 horsepower gain with 93. I have run through the mountains of Virginia and North Carolina from Long Island 7 times in the last 14 months and will only run premium. It's that much better.
 

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Where does he recommend using 89 for non towing driving??
The RL and Pilot engines are most efficient and powerful when using 90 octane fuel, as per a statement by Gary Flint. That's why Honda recommends premium when towing or hauling, but 87 is ok for normal driving. As where you can find this info is on this forum and if I had the time to search it I would. I didn't make this up

Here it is: http://www.ridgelineownersclub.com/forums/showpost.php?p=231907&postcount=62

Also, here's what jnc2000 had to say: Re: fuel octane???
torque converter lock up = better FE.

By utilizing the transmission most efficiently I'm able to ascend grades while holding 5th gear and tc keeps it lock. This in turn gives me better fuel economy. Otherwise, the truck would unlock, downshift to 4th, and sometimes 3rd gear to maintain speeds while traveling up hill.

Yes, all trucks / cars sometimes down shift to according to the terrain. But if I'm able to control the shifting, and manipulate things to my advantage - I will. It's a win / win for using 89 on my daily commute.

Any increase in mpg under 89 octane further decreases my cost per mile.

89 octane (under my driving conditions) lends it self to a lower cost per mile / and better FE.

Now, I understand those who have the advantage of driving on flat terrain may not see the same results. But, for my daily driving I'll stick to "top tier gas" using 89 or above depending on the station.
Last edited by jnc2000; 08-19-2010 at 12:21 PM. Reason: fuzzy math

The higher octane allows the torque converter to shift to a higher stall speed. This has been explained by on ROC by Gary Flint himself. Higher octane fuel may net higher FE for those who do utilize it to it's full potential.
 

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I'll throw in my two cents. From the very first day I owned my truck (bought used with 75k miles on it), I started off with 87 octane. I noticed the mileage was average at best for the first two tanks. I figured I'd give 89 a shot. The truck felt better to me and I gained about 1.5mpg on the very first fill up. To make sure it wasn't a fluke, I filled up several more times with 89 and saw the same results. I used to drive about 50-55 miles per day in commuting, so the 10 cent premium for 89 octane was certainly worth it. On a trip through down-state WV, VA and TN a few summers ago, I started the trip with 89 octane. The truck was routinely at over 4000RPM trying to maintain 75mph up the mountains and I saw a 19mpg average. We filled up with about 200 miles left on the trip down at a station that only had 87 and 93. Being that I wouldn't put 87 in my truck again, I bit the bullet and used 93. The truck was almost transformed. It didn't shift nearly as much and it never had to get over 4000RPM to maintain speed. It was smoother and felt more powerful and I got 19.5-20mpg on the return trip. Now that I drive about 7-10 miles per day, I fill up once a month with 93. Gary Flint has said that 90-91 is the optimum octane rating for the RL at sea level and it cannot advance itself any farther with higher octane fuel. So, at higher elevations, 89 might be ok but 91, 92 or 93 octane (whatever is available) is going to be the fuel that will get you the most efficiency and power. Many will swear that they've only used 87 and have never had a problem. That's probably true, but they may have never tried 93 either.
 

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We don't even have 93. I have used 91 and really did not notice any advantage over 89. But with 89 I have seen a bit more power and maybe a skosh better mileage. It is what I run consistently and use top tier stations. The ones with decent prices and high turnover. Around these parts that usually means Shell. Chevron always seems to be priced higher. I like Costco also, just not that convenient for me. They claim to only purchase from top tier companies.
I suppose 91-93 may buy you a little more power, but generally that difference is not even significant except very close to, and at wide open throttle (WOT). Which is not a very normal condition for a Ridgelline. At least not how most of us would drive one.
Similar curves were plotted on a 2004 MDX on their forum. Any improvement was at WOT. It is not worth the 10 pennies a gallon for me. Although a slight mpg improvement might offset that some.
 
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